Differences between astronomy, astrophysics and cosmology?

What is the main difference between , , and ?   I have the impression that astronomy is a subject that runs parallel to physics but it is outside the physics field. This is based on the division of departments present in many universities: the department of physics being separated from the department of astronomy. The difference between cosmology and astrophysics is more obscure to me. I have the impression, though, that cosmology is more concerned with the structure of spacetime and universe models while astrophysics is more concerned with stellar life cycles, physical properties of stars, galaxies etc.  Which is the field that had more activity/ scientific breakthroughs recently?  In real life, are those classifications even important? Are there many differences between the education process of a future astronomer, astrophysicist or cosmologist?  Somebody, please, give examples of famous astrophysicists, cosmologists and astronomers at the present time.


I have a secondary IP on my ens160 interface and I don't know why :) System is Ubuntu 17.10. Any hints where to dig here?  1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00     inet 127.0.0.1/8 scope host lo        valid_lft forever preferred_lft forever     inet6 ::1/128 scope host        valid_lft forever preferred_lft forever 2: ens160: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000     link/ether 00:0c:29:07:bd:e3 brd ff:ff:ff:ff:ff:ff     inet 192.168.0.5/24 brd 192.168.0.255 scope global ens160        valid_lft forever preferred_lft forever     inet 192.168.0.165/24 brd 192.168.0.255 scope global secondary ens160        valid_lft forever preferred_lft forever     inet6 fe80::20c:29ff:fe07:bde3/64 scope link        valid_lft forever preferred_lft forever   192.168.0.5 is my static ip, configured via netplan:  network:   version: 2   renderer: networkd   ethernets:     ens160:       dhcp4: no       dhcp6: no       addresses: [192.168.0.5/24]       gateway4: 192.168.0.254       nameservers:         addresses: [8.8.8.8,1.1.1.1]


How to set identity_insert to on in SQL Server

I get the command set identity_insert table_name on;, but for some reason it is not actually changing the attribute. I've done it with the account that I created the table with, and I've also created an 'admin' account and gave it permissions to do anything (to the best of my knowledge).    Whenever I run the command under either account I get the result of '0 rows affected', then I am unable to run the query to insert the rows I wish to insert with the following error:     Cannot insert explicit value for identity column in table 'table_name' when IDENTITY_INSERT is set to OFF.     Additionally I've tried to include the schema name in the query like:  set identity_insert mySchema.table_name on;    but I get the following error:     Cannot find the object "mySchema.table_name" because it does not exist or you do not have permissions.   Also of note, my project looks like:  localhost\SQLEXPRESS -Databases --System Databases --mySchema   Does anyone know a solution to this problem?


Product Snippets with JSON-LD + Schema.org - Are there any live examples in Google index?

** EDIT Feb 2016 - Finally JSON-LD seems to be working now in SERPS, with extremely fast changes-to-index time, assuming you have everything with Google merchant center feeds syncd and linked. Make sure the price, stock, and identifier are the same on your JSON-LD as it is on the Google shopping feed. New organization->localbusiness types are live, organization reviews are live... however JSON-LD feed alt= endpoints still do not exist, the homepage schema defining custom site name is not active, and G support for schema itemList/dateModified is still questionable. You can still get pagination results and date modified snippets by using literal text strings in your view/template Showing 1-28 of 8977 Results (321 Pages)and Last updated on February 3rd 2016. To proceed to a deeper exploration of JSON-LD support, see these:       Original Post Below: Google seems to be flip flopping JSON-LD -> Schema.org product [or other types of] snippets. The snippets verify without error in both the testing tool and long term (10+ months) across 5 properties in GWT search console. The snippets have been applied to index, removed, applied, and removed again, seemingly not being applied again in regards to various facets. Since they worked in the past via microdata, and were applied long term, I assume it's due to the switch to JSON-LD. I have not found any official docs nor examples that say "Google will support and render products snippets that use JSON-LD". Same thing with breadcrumb snippets and review looping. All I see is a handful of Google examples for events, movies, recipes, very basic [incomplete] organization etc. This seems strange to me considering the sheer amount of ecom pages using product snippets trumps the amount of movies, recipes, and events combined. So the question is, does Google officially support, index, and render product markup using JSON-LD? If so, can anyone point me to a live example to verify this? ** This question is not intended to be "opinion/recommendation based"....im looking for a specific link and subsequent SERP result [evidence] showing that JSON-LD products/etc are indeed rendered within Google.com realm as of late August 2015. ** EDIT Nov 16 2015 - Another annoying caveat has been found. Google merchant center validates certain shopping feed fields such as condition, stock, and price against live microdata. However, it seems to not recognize JSON-LD.... although, as stated above, it's recommended to use in all the G examples, and it validates the snippet test. So due to this, your merchant center account could be suspended because of "differences in presentation data"


Adding file name to attribute field using Calculate Field?

Does anybody know how to add the shapefile name to a field in the file's attribute table?  I've found a description:     'You have to use inline variable in CalculateField like %Name% in   expresssion so that whatever the name of the file is, the string will   be inserted based on Name of the dbase file !'   I've tried to CalculateField tool with %Name%, but I got message:  Executing: CalculateField "2011-11-6 15_41_point" DBFName %Name% PYTHON # Start Time: Thu Dec 08 23:34:23 2011 WARNING 000405: No records within table Succeeded at Thu Dec 08 23:34:24 2011 (Elapsed Time: 1.00 seconds)   Where is my mistake?


$\gcd(ab,c)$ equals $\gcd(a,c)$ times $\gcd( b, c)$

Let $a,b,c$ be integers, prove that if $\gcd(a,b) =1$ then $\gcd(ab,c) = \gcd(a,c)\times\gcd(b,c)$  I don't know what to do after I got the combinations of $ab$ and $c$.


We are conducting a test on a rare disease. A positive result means that, according to the test, the subject is infected. The following characteristics are known about the test and the disease: If a person is infected, the person has a $95\%$ chance of testing positive. When a healthy person is tested, the test has a $99\%$ chance of giving a negative result. A mere $0.1\%$ of the population is infected with the disease. If a person is tested positive for the disease. What is the probability that the person actually has the disease? I don't understand how to write the conditional probabilities if someone can explain to me than I should know how to solve it, but I'm not sure how to convert the text into the mathematics language.


What is the right ffmpeg output format for a v4l2-loopback device?

Following the guide in  I did:  $ sudo modprobe v4l2loopback $ ffmpeg -f x11grab -r 15 -s 1280x720 -i :0.0+0,0 -vcodec rawvideo -pix_fmt yuv420p -threads 0 -f v4l2 /dev/video0   The device /dev/video0 shows up as expected but the ffmpeg command fails with following output:  $ ffmpeg -f x11grab -r 15 -s 1280x720 -i :0.0+0,0 -vcodec rawvideo -pix_fmt yuv420p -threads 0 -f v4l2 /dev/video0 ffmpeg version 4.0 Copyright (c) 2000-2018 the FFmpeg developers ... [x11grab @ 0x559767794cc0] Stream #0: not enough frames to estimate rate; consider increasing probesize .... [v4l2 @ 0x55976779e6c0] ioctl(VIDIOC_G_FMT): Invalid argument Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument Error initializing output stream 0:0 --  Conversion failed!   I already tried to follow the suggestions below the answer to no avail. I noticed that v4l2 is listed as demux only in ffmpeg -formats. Does that mean I can't use it for output to /dev/video0? If so, what should I use instead? I tried h264 but that crashes after ~1000 frames with following error message:  $ ffmpeg -f x11grab -r 15 -s 1280x720 -i :0.0+0,0 -vcodec rawvideo -pix_fmt yuv420p -threads 0 -f h264 /dev/video0 ffmpeg version 4.0 Copyright (c) 2000-2018 the FFmpeg developers ... [x11grab @ 0x55da61e29cc0] Stream #0: not enough frames to estimate rate; consider increasing probesize ... File '/dev/video0' already exists. Overwrite ? [y/N] y .... Error writing trailer of /dev/video0: Invalid argument .... Conversion failed!


Can my UK university have my US visa cancelled?

I am an international student in the UK. I have a group field trip going to Las Vegas in may which I have joined. I mentioned I will be going to Vegas as part of my university group in DS160. I do have b1/b2 visa for the trip. But for work reasons, I could not go now. My university has provided a supporting letter for visa interview which was taken by us embassy visa officer.  The university personnel advised me that they will email my passport details to US Embassy and asked to either revoke or cancel my visa.  Can they do that?


In VMware Workstation is there a way for a Kali Linux virtual machine to be able to sniff packets with the wireless NIC?

I'm new to Kali Linux.  I'm running Kali Linux inside VMware Workstation.  I have a Ralink USB wireless NIC connected to my PC.  I want to enable Monitor mode which is simply done with the airmon-ng start wlan0 command. But there's no wlan0 adapter to be found. When I enter the ifconfig command I only see eth0 and lo:


I am working on a program that continues to ask the user to input a flight code i.e FR201. The program would then read the flight code and return the airline and the flight number.. but i'm having trouble getting it to work correctly and am just getting "invalid input".  Here is what I have tried, any help is appreciated!   import java.util.Scanner; public class flightcode{ public static void main(String[]args) {     String s2;     do{      Scanner s1 = new Scanner(System.in);     System.out.println("Enter a number");       s2 = s1.nextLine();     int num = s2.length()-2;     int s3=0;       if(s2.substring(0,1)=="EI")     {      s3 = 1;     }      else if(s2.substring(0,1)=="FR")     {     s3 = 2;     }     else if(s2.substring(0,1)=="AF")     {      s3 = 3;     }     else if(s2.substring(0,1)=="AA")     {      s3 = 4;     }     else if(s2.substring(0,1)=="IB")     {      s3 = 5;     }        switch (s3)      {          case 1: System.out.println("Airline: Aer Lingus - Flight number:" + s2.substring(2)); break;         case 2: System.out.println("Airline: Ryanair - Flight number:" + s2.substring(2)); break;         case 3: System.out.println("Airline: Air France - Flight number:" + s2.substring(2)); break;         case 4: System.out.println("Airline: American Airlines - Flight number:" + s2.substring(2)); break;         case 5: System.out.println("Airline: Iberia - Flight number:" + s2.substring(2)); break;         default: System.out.println("Invalid input"); break;      }     }         while(s2!= "END");       } }


XML parsing - ElementTree vs SAX and DOM

Python has several ways to parse XML...  I understand the very basics of parsing with SAX.  It functions as a stream parser, with an event-driven API.  I understand the DOM parser also.  It reads the XML into memory and converts it to objects that can be accessed with Python.  Generally speaking, it was easy to choose between the two depending on what you needed to do, memory constraints, performance, etc.  (Hopefully I'm correct so far.)  Since Python 2.5, we also have ElementTree. How does this compare to DOM and SAX? Which is it more similar to? Why is it better than the previous parsers?


Total Energy of the ISS orbiting the Earth

I had a bit of confusion earlier about a discussion in astrophysics.   I was reading that the ISS orbits the earth at $8 kms^{-1}$ but then when I calculated the total energy that the ISS had, I was considering:   It's Kinetic Energy $\frac{1}{2}mv^2$ It's Gravitational Potential Energy $-\frac{GMm}{r}$   where    $m$ is the mass of the ISS $M$ is the mass of the Earth $v$ is the speed of the ISS   When I did my calculations, something got me confused.   Using the following data:     ISS circles the Earth at a height of $4.0 \times 10^5$m.     ISS has a mass of $4.2 \times 10^5$ kg    The radius of the Earth is $6.4 \times 10^6$ m    The mass of the Earth is $6.0 \times 10^24$kg   It turned out the magnitude of the Gravitational Potential Energy is greater than the magnitude of the Kinetic energy.  $$E_K < |E_{GPE}|$$  But in the lecture notes I was reading for astrophysics, the overall Energy is negative as you add both Energies together.   Is it possible for the energy of an object to be negative, and is it valid in this case?  I was thinking to add the magnitudes of both $E_K$ and $E_{GPE}$ as I assumed the total energy of the ISS was equal to the sum of these energies, hence giving a positive value.


To what extent is a scheme morphism determined by its topological map?

I am just beginning to learn scheme theory. This question is aimed at getting a feel for something so apologies in advance for the lack of precision.  I am struck by the following difference from the theory both of varieties and smooth manifolds:  In the categories both of varieties and of smooth manifolds, a morphism is completely specified by what it is doing on the topological spaces, since the elements of the structure sheaf (regular functions for varieties, smooth functions for manifolds) are determined by their pointwise values.  But in the category of schemes, to specify a morphism $f:X\rightarrow Y$ we need to separately specify the underlying topological map $f:X\rightarrow Y$ and the sheaf map $f^\#: \mathcal{O}_Y\rightarrow f_*\mathcal{O}_X$.  In spite of this, it seems to me that the topological map puts strong constraints on the sheaf map. For example, if $X=\operatorname{Spec}B,Y=\operatorname{Spec}A$ are affine schemes, the morphism is determined by a ring homomorphism $A\rightarrow B$; the topological map is how the primes contract under that ring homomorphism. If I know how all the primes are contracting, this does not leave the homomorphism a lot of room to wiggle. I request help in thinking about exactly how much room there is:     "How many" different morphisms are possible between schemes $X,Y$ with the same topological map $f:X\rightarrow Y$? "How different" can they get? What kinds of conditions on $X,Y$ limit this flexibility?   (For example, if $X,Y$ are integral, in which case elements of the structure sheaves are "determined by their pointwise values" in the residue fields $\kappa(p)$, does the topological map force a particular sheaf map as it does for varieties and manifolds?)


What accounts for the flow of liquid, Net force or Net Pressure?

Consider a tube having liquid kept on a horizontal plane. Now suppose two forces of unequal magnitude act on the two open surfaces of the liquid, such that area of one surface is greater than the other. Also the forces act such that the force acting on the surface with greater area is greater than the other force acting in the surface with smaller area, but the pressure exerted by the force on the smaller area is greater than the pressure exerted by the other force. Where will the liquid flow in this case? Towards the surface with greater area(consider that it is situated on the right) or the surface with smaller area (left). I hope I can make sense. Thanks in advance.


What's the pdf of the square of a normal distribution?

Let $X\sim N(\theta, 1)$ where $\theta \in \mathbb R$. Compute the pdf of $X^2$. Current work: The pdf of X is $f=\displaystyle \frac{1}{\sqrt{2\pi}} e^{-\frac{1}{2}(x-\theta)^2}$. We might try the method of finding the cdf of $Y=X^2$ and then converting that into the pdf. It goes $F(y)=Pr(Y\le y)=Pr(X^2\le y)=Pr(-\sqrt {y}\le X\le \sqrt {y})=...$


When does the placement of a resistor matter?

I've been a programmer for years but am very new to electronic engineering. So far I see people saying it doesn't matter where a resistor goes in your LED circuit as long as it is present, but it sounds like that's the nature of the basic LED circuit.  When does the placement of a resistor start to become important?


how to print an enumerated variable in C?

I am using enumerated type declaration. I can't print it.  So far I have written the following code. The question is how to print a enum type variable?       #include <stdio.h> int main()     {         enum day {monday,tuesday,wednwsday,thrusday,friday,saturday,sunday};         enum day week_st, week_end;     week_st = monday;     week_end = friday;     if(week_st == monday)     {         printf("%s\n",week_end);     }     return 0; }


Rearranging people so that no one is in the same spot

I am not sure how to approach this problem:  $n$ people are seated in numbered chairs $1$ to $n$. Let $N$ be the number of ways the people can be reseated so that no one is in the same chair as before. Show that $N=n! \sum_{k=0}^n \frac {(-1)^k}{k!}$.  I feel like the way to do this is to come up with a way to count all the seating arrangements, yet I am not sure how to take into account the seat where the person already sat into account when counting them. Because it would seem that there is $n-1$ possible places to sit at, yet placing the first person does not eliminate one possibility for everyone...  Any help is appreciated. Thank you in advance.


I want to find the function $f(x)$ that satisfies the equation.

I have encountered with this equation while solving an integral. The integral result was $$ \left. \sum_{n=0}^{m+1} \left( \frac{d^n}{d x^n}\left( x^{m-1}\prod_{k=1}^{2}\left(\lambda_{k}.x+m(1-\lambda_{k})\right)\right)\right)\right|_{x=0}=m\lambda_{1}\lambda_{2}+m^2 $$ where $m$,$\lambda_{1}$ and $\lambda_{1}$ are positive constants. Now suppose I have $m_1$ and $m_2$, then I have $$ \left. \sum_{n=0}^{N} \left( \frac{d^n}{d x^n}\left( f(x) \right)\right)\right|_{x=0}=m_{1}\lambda_{1}\lambda_{2}+m_{1}m_{2} $$ What is the value of $N$ and function $f(x)$ that satisfies the previous equation. Or what should we modify on the first equation to meet the last one. Note: $m_{1}\neq m_{2}$.


Are there tours available from Seoul to the Korean Demilitarized Zone?

I am planning to visit the Korean Demilitarized Zone while staying in Seoul and would like to get tour options. Anyone has done this?  Prices, schedule and tips are most welcome.


Want to see which numbers in Column A are not in Column B

I would like to see which numbers in Column A are not in Column B, with "Yes" or "No" displayed in Column C. I am trying to find a text with 10 numeric digits.  More specifically, I want to know which digits are in column A that are not in Column B. These are ISBNs of books that often begin with 0. Is there a format that would work better? As indicated, the results should be in Column C.  Example Data


How do I write formulas in Microsoft Word using LaTex

I would like to write formulas in word using LaTex, but I don't know how. I am new to LaTex. Can someone please help me?


I can't figure out what's wrong with this. According to , it should work. Thanks!  [Desktop Entry] Version=1.0 Name=D3GO Comment=D3GO televizija preko interneta Exec=~/D3GO/D3GO Path=~/D3GO/ Icon=~/D3GO/D3GO.png Terminal=false Type=Application Categories=Application;


Check radio button when clicking it's div-container

I wrote this simple script, and it's seems to work fine, but only once. I click div-container - the radio within gets checked. I click another div - another radio gets checked. But now, when I click the previous div again, the radio won't get checked.  Here's the code:  $('div').click(function () {    $(this).find('input:radio').attr('checked', true); });   And example:   Thanks for suggestions!


This is a tooltip in an application:     Identifies the site name to which the GL code belongs to.   Can I say that it is incorrect to use "to" twice here and we should remove 1 of them?  Other examples:       Identifies the vendor to which the port speed is associated with.   Provides the vendor to which the milestone is associated with.   (They are both tooltips, too)  The repetitions here are incorrect, aren't they? Please confirm.


Give an example about limits: $\lim\limits_{x\to0}f(x^{2})$ exists but $\lim\limits_{x\to0}f(x)$ does not.

Can someone help me find an example where $\lim\limits_{x\to0}f(x^{2})$ exists but $\lim\limits_{x\to0}f(x)$ does not.      Thanks.


My phone is a Nokia 6.1. I'd like to do a factory reset, but preserving:   my personal files the settings of all apps the data saved by all apps (e.g. the alarms saved by the stock Clock app) the collection of apps (I want them to be reinstalled after the reset)   Does the "Settings -> Advanced -> Backup" Android feature do all that? If no, then what part does it do?


If $f$ is an increasing function defined on $[a,b]$ . Then, $f$ has countable number of discontinuities

If $f$ is an increasing function defined on $[a,b]$ . Then show that the set of discontinuities of $f$ is countable and that $f$ has points of continuity in every open subinterval of $[a,b]$  Attempt: I have trouble understanding why the number of discontinuities of $f$ should be countable. For example, if we define a function which is increasing but different at each point in the interval $[0,1]$, then, there can be uncountable number of discontinuities.  I think if we prove that the number of discontinuities is countable, then we can prove that the function has points of continuity in every open interval of $[a,b]$.  Please help me understand intuitively why $f$ must necessarily have countable number of discontinuities. Suppose, $f$ has an uncountable number of discontinuities, then what can happen?  Thank you for your help.


Why wasn't Sabretooth the original Weapon X subject? Wasn't he trustable, or were his healing powers inferior?


I've created a settings page for my theme, and I'd like to be able to set the frontpage from there, but I don't know how I can change the frontpage in code?  This is the setting:  $node_type = "page"; $result = db_query(     'SELECT n.nid, n.title FROM {node} n WHERE n.type = :type',     array(':type' => $node_type) ); $options = array(); foreach ($result as $record) {     $options[$record->nid] = $record->title; }  $form['static_nodes']['front_page_id'] = array(     '#type'        => 'select',     '#title'       => t('Frontpage'),     '#options'     => $options,     '#description' => t('Set the page used as the frontpage.'),     '#default_value' => theme_get_setting('front_page_id'), );


how to extrude an svg on surface of cylinder

I want the fish that sits on the cylinder to extrude out off the smooth surface Much like a fish stamp but on a curved surface.  I can get the fish curved on the surface but cannot get it to extrude I have a cylinder and have imported an SVG and shrinkwrapped it top a cylinder.  How do I extrude the svg on surface of cylinder to it is raised/extruded (embossed)? I tried to add midifier > solidify but the extrusion went crazy


How do we know a quantum state isn't just an unknown classical state?

When an observer causes the wave function of a particle to collapse, how can we know that the wave function was not collapsed already before the measurement?  Suppose we measure the z-component of the spin of an electron. After the measurement, it is entirely aligned along the measured direction, e.g. the +z-direction. Before the measurement we need to assume that a probability distribution proportional to $|\Psi|^2$ of the two allowed directions is present.  If we repeat the measurement with many identically prepared electrons, we should see such a distribution finally. For example, we could measure 40% spin-down and 60% spin-up.  However, it seems we could also assume that all of these particles have a defined spin-direction before we measure them.  What is an intuitive (being aware that quantum phenomena as such are rarely intuitive) explanation for why we cannot simply assume that the spin was already aligned completely in that measured direction?    With regards to the suggestion that this two-year old question is a duplicate , I would like to point out that my question isn't limited to entanglement, but asks about a very fundamental principle in quantum mechanics, and as such is not a duplicate.


The above image is what I have created so far, still prototyping, just got started scripting within Blender Would like to be able to collapse each box, which contains light properties, like the image below (from Luxcore). Does Blender have this option or do I have to build it from scratch?  I have looked through the code, but can't seem to make sense of it...


How do I use superposition to solve a circuit?

Yes, this is a pedagogical question. While answering another recent question, I wanted to refer the OP to concise instructions for using superposition to solve circuits. I found that all the easily found resources online were somewhat deficient. Typically they were unclear about what kinds of circuits superposition applies to, or about the actual method to apply the superposition theorem to a circuit problem. So,   What kinds of circuits can be solved by superposition?  How are different kinds of sources treated when solving by superposition?  What are the steps to solve a circuit using the superposition theorem?


Why can't you hear music well over a telephone line?

Why can't you hear music well well over a telephone line?  I was asked this question in an interview for a university study placement and I unfortunately had no idea.  I was given the hint that the telephone sampling rate is 8000 samples per second.


How does the socket API accept() function work?

The socket API is the de-facto standard for TCP/IP and UDP/IP communications (that is, networking code as we know it). However, one of its core functions, accept() is a bit magical.  To borrow a semi-formal definition:     accept() is used on the server side.   It accepts a received incoming attempt   to create a new TCP connection from   the remote client, and creates a new   socket associated with the socket   address pair of this connection.   In other words, accept returns a new socket through which the server can communicate with the newly connected client. The old socket (on which accept was called) stays open, on the same port, listening for new connections.  How does accept work? How is it implemented? There's a lot of confusion on this topic. Many people claim accept opens a new port and you communicate with the client through it. But this obviously isn't true, as no new port is opened. You actually can communicate through the same port with different clients, but how? When several threads call recv on the same port, how does the data know where to go?  I guess it's something along the lines of the client's address being associated with a socket descriptor, and whenever data comes through recv it's routed to the correct socket, but I'm not sure.  It'd be great to get a thorough explanation of the inner-workings of this mechanism.


Understanding the probability of a point, it's zero but point is observable.

Okay so this might be a basic question/stupid question, but I cannot find an answer for it.   So let's say we have a continuous random variable that returns a value in 0, 1. I know that the probability to observe any single given point in this interval is zero (one point over infinite). How come I can observe this point that has no probability to be observed ?


Are there any other methods to apply to solving simultaneous equations?

We are asked to solve for $x$ and $y$ in the following pair of simultaneous equations:  $$\begin{align}3x+2y&=36 \tag1\\ 5x+4y&=64\tag2\end{align}$$  I can multiply $(1)$ by $2$, yielding $6x + 4y = 72$, and subtracting $(2)$ from this new equation eliminates $4y$ to solve strictly for $x$; i.e. $6x - 5x = 72 - 64 \Rightarrow x = 8$. Substituting $x=8$ into $(2)$ reveals that $y=6$. I could also subtract $(1)$ from $(2)$ and divide by $2$, yielding $x+y=14$. Let $$\begin{align}3x+3y - y &= 36 \tag{1a}\\ 5x + 5y - y &= 64\tag{1b}\end{align}$$ then expand brackets, and it follows that $42 - y = 36$ and $70 - y = 64$, thus revealing $y=6$ and so $x = 14 - 6 = 8$. I can even use matrices! $(1)$ and $(2)$ could be written in matrix form: $$\begin{align}\begin{bmatrix} 3 &2 \\ 5 &4\end{bmatrix}\begin{bmatrix} x \\ y\end{bmatrix}&=\begin{bmatrix}36 \\ 64\end{bmatrix}\tag3 \\ \begin{bmatrix} x \\ y\end{bmatrix} &= {\begin{bmatrix} 3 &2 \\ 5 &4\end{bmatrix}}^{-1}\begin{bmatrix}36 \\ 64\end{bmatrix} \\ &= \frac{1}{2}\begin{bmatrix}4 &-2 \\ -5 &3\end{bmatrix}\begin{bmatrix}36 \\ 64\end{bmatrix} \\ &=\frac12\begin{bmatrix} 16 \\ 12\end{bmatrix} \\ &= \begin{bmatrix} 8 \\ 6\end{bmatrix} \\ \\ \therefore x&=8 \\ \therefore y&= 6\end{align}$$  Question Are there any other methods to solve for both $x$ and $y$?


C#__ adding string into string using length

In my program, I'm trying to add a comma for a number that's length is more than 3. For example if number is 1000, it should output 1,000. However I can't find out how to add on remaining numbers after I put comma into first one. The code below is what I've got: // if the answer is more than 999 string answerThousand = Convert.ToString(lbl_NumResult.Text);  if (answerThousand.Length > 3)  {     lbl_NumResult.Text = answerThousand[1] + "," + answerThousand[ /* What must be here to add remaining numbers? */]; }


I am trying to implement a matrix class.  Class Definition  template <typename T> class Matrix { private:     int size;           //size of matrix     T value;     T ** M; public:     Matrix(int m = 2);     Class implementation  /* Matrix constructor */ template <typename T> Matrix<T>::Matrix(int m) : size(m), value(0) {     M = new T*[size];     for (int i = 0; i < size; i++)     {         M[i] = new T[size];         for (int j = 0; j < size; j++)         {             M[i][j] = value;         }     } }   This is how I create an object:  Matrix<int> A = Matrix<int>(3);   I keep getting this error:      Error 2   error LNK2019: unresolved external symbol "public: __thiscall   Matrix::Matrix(int)" (??0?$Matrix@H@@QAE@H@Z) referenced in   function _main   Any ideas what can be causing this?


How to get a CD out of MacBook disc drive

...the drive is 'whirring' etc, but not ejecting the cd.  I restarted and held down the mouse on the start-up chime -- that worked once; but I then put the cd back in and that method no longer works.  How do I get the cd out?  Thanks,


I have tried a number of the solutions listed on my stove top to no avail.  The stains are white, like water stains & I can't figure out what they could be.  Any suggestions?


I am using the standard article class and bib style unsrt with LaTeX and BibTeX.  I would like to customize individual biblabels in my list of references, for instance starring certain items as follows:     [1] A. Uthor ...      *[2] B. Uthor ...      [3] C. Uthor ...   where the labels should be right-aligned so that the starred ones stand out.  Thanks to this forum, I know how to customize all the labels with:  \makeatletter  \renewcommand\@biblabel[1]{\mbox{$\star \left[ \right.$}#1\mbox{$\left. \right]$}}  \makeatother   but how can I customize only specific ones?  A solution based on BibTeX tags would be prefered, but others will be considered.


Is it possible to define in pgfplots that y should correspond to Y cm in my plot?   I know how to do this in tkz-fct, so let me add an tkz-fct example to make more clear what I want:  \documentclass{article}  \usepackage{pgfplots} \usepackage{tkz-fct} \usetkzobj{all}  \begin{document}  \begin{tikzpicture}[scale=.5] \tkzInit[xmax=10,ystep=3,ymax=10] \tkzAxeXY \tkzGrid \tkzFct[color=red, thick,domain=0:10]{\x} \tkzFct[domain=0:10]{\x**2} \end{tikzpicture} \begin{tikzpicture}[scale=.5] \tkzInit[xmax=10,ystep=1.5,ymax=10] \tkzAxeXY \tkzGrid \tkzFct[color=red, thick,domain=0:10]{\x} \tkzFct[domain=0:10]{\x**2} \end{tikzpicture}   \end{document}     In one case 3 corresponds to 0.5 cm on the y-axis in the picture, in the other case 1.5 corresponds to 0.5 cm on the y axis. This is achieved by using the scale=0.5 option together with the ystep option.  Not that it is important for me to have grids as in the tkz-fct example.


Do you really answer “How do you do?” with “How do you do?”

I'm a non native speaker of English. In our learning we were told that when we say hello to someone we use equivalent phrase:      How do you do?   In response we do say:     How do you do?   But I'm unsure about the usage in the USA or UK. I haven't heard from them. I'm an Indian.  Is this the correct way of introducing someone?


How to show a blank page in "New Tab" within Google Chrome?

I am annoyed by the thumbnails that are shown when opening a new tab in Google Chrome. I want to see a blank page. How to do that?


Inner automorphisms form a normal subgroup of $\operatorname{Aut}(G)$

For an arbitrary group $(G,\cdot)$ let $\operatorname{Aut}(G) = \{f: G \to G \mid f \text{ is an isomorphism}\}$ be the set of all automorphisms of the group $G$. We assume that $(\operatorname{Aut}(G),\circ)$ where $\circ$ is composition of mappings is a group.  1) Prove that for arbitrary $a \in G$ there is an automorphism $p_a: G \to G;\quad p_a(x) = a^{-1}xa$.  2) Prove, that $\operatorname{Inn}(G) = \{p_a \mid a \in G\}$ is a normal subgroup of $(\operatorname{Aut}(G),\circ)$.


What should you do after changeing thousands of URLs?

I currently changed 50,000+ URLs of my website something similar to example.com/articles/new-slug from example.com/old-slug.  What I have done so far.   Add 301 redirection for all old articles to new one. Remove old sitemap from Google Web Master Tools and Add new sitemap.   What else should I do?


I'm newbie when it comes to UX, there's a thing I don't understand and couldn't find answer to that. So I hear every now and then that modal on modal is bad. But I don't understand why and no one could explain it to me so far.   For example: We have web application where you can work on a document and you can invite people. Inviting people opens modal - it's self contained flow of permission management. You can invite, remove and change permissions of users. If you start changing permissions or removing people then you need to press "Save" button to confirm it all. If you try to leave modal without confirming then another small modal "You have unsaved changes, do you want to proceed?" is displayed. So I heard people saying this is "bad UX/bad solution", but why? This is exactly what Google implemented in their Google Docs. What would be "good UX" then?


Either I need clarification on the 'Not an answer' flags or it needs a new description

First of all - I'm not going to bitch and moan to moderators in this topic. I'm here to ask clarification because I've had a flag declined and I really have no clue what I did 'wrong', or how to avoid the same 'mistake' in the future.  I flagged  as Not an answer, because the description of that flag states:   Not an answer. This was posted as an answer, but it does not attempt to answer the question. It should possibly be an edit, a comment, another question, or deleted altogether.   It was declined as follows:    As I said in the comment below, before flagging it, it's technically a completely valid comment, there's nothing wrong with it on its own, it just does not remotely attempt to solve the question in any way. It's like someone asks "What's your favorite color?" and you answer "Today's Tuesday". While a perfectly correct statement on its own, it does not attempt to answer the question, and should have been a comment. Which is the exact description of the Not an answer flag, so I selected that flag, and it was declined because I should not have flagged it for "technical inaccuracies or wrong answers".  I was under the impression that all remarks that might be technically correct, but do not solve issues directly related to the question at hand, should be added as comments, not answers, since they pollute the 'Knowledge Base' aspect of the site for future visitors. If this is not enforced, the flag should be renamed to "Not relevant to question" or something like that.  (the original post also contained a reference to another declined flag, but that was sufficiently explained to stem from different interpretations of what is considered 'spam' and thus removed as not to pollute the discussion on the other one)


After installing per the :  sudo dpkg --add-architecture i386  wget -nc https://dl.winehq.org/wine-builds/winehq.key  sudo apt-key add winehq.key sudo apt-add-repository 'deb https://dl.winehq.org/wine-builds/ubuntu/ bionic main' sudo apt update sudo apt install --install-recommends winehq-stable   Staring Wine fails:   wine start /unix %f 0009:fixme:exec:SHELL_execute flags ignored: 0x00000100 0009:fixme:exec:SHELL_execute flags ignored: 0x00000100 0009:fixme:exec:SHELL_execute flags ignored: 0x00000100 0009:fixme:exec:SHELL_execute flags ignored: 0x00000100 0009:fixme:exec:SHELL_execute flags ignored: 0x00000100 0009:fixme:exec:SHELL_execute flags ignored: 0x00000100 0009:fixme:exec:SHELL_execute flags ignored: 0x00000100 0009:fixme:exec:SHELL_execute flags ignored: 0x00000100 0009:fixme:exec:SHELL_execute flags ignored: 0x00000100 0009:fixme:exec:SHELL_execute flags ignored: 0x00000100 Application could not be started, or no application associated with the specified file. ShellExecuteEx failed: Invalid window handle.   This is the error code I get when I try to open Wine in Terminal. I first ran Wİne on Terminal and it said it couldn't find Mono and Gecko and said it can install it for me. I clicked ok and it installed Mono without any problem but with Gecko it got an error and couldn't install it. It was able to install it in the second try and I ran Wine again, but I got the error above. Did I do anything wrong? I should also mention, when I try to open it from /usr/share/applications nothing happens.


Is there a home for a question on calculating cost of using Storage as a Service?

There is a lot of hype being generated by the distributed storage solutions:        They (supposedly) offer low-cost storage, and also pay for people to share their storage for others to use.  However, it is extremely difficult to find out how much it costs in everyday money to use these systems (or how much one would get paid), as they are based around their own crypto-currencies (which prices are often quoted in Bitcoin to add further obfuscation). The duration of storage adds further complexity to making a comparison.  As such, it's extremely difficult to know how much each service costs or pays out individually, and even more difficult or to make a fair comparison between them.  In my searches, people are looking for some real-world figures and/or a way to calculate them - but they are not readily available.  I would like to ask a question along the lines of:     How can I work out which is the cheapest storage solution [of the three], based on storing 1TB of data for a month?   I tried to ask the analogous question with respect to earnings  but it was closed as off-topic.  I feel that this question would add value in clarifying very murky waters, but I'm not sure where to post it, or even if it would be on-topic for any SE site.  If it's not on-topic for SE, any pointers as to where to ask it outside?


I'm working with ArcGIS 10.2 for Desktop and OS Windows 7.   I need to set numeric vales from Zero back to NULL, but I can't from the field calculator.  I'm working with  a vector file and I need to display NULL in one column that shows 0 (Zero) as default value.  -------- Edit------- I am adding the error messages that he received  Translation:  An error occurred during the process.  Please consult the Geoprocessing Results Window to obtain more details.  Error at bottom, translation:  The values of the selected column can not be set to null because the field in the database is defined as "Not Null".


What's the right size of Polarizer and how do I know if it works with my camera?

I've just recently joined the world of photography with a DSLR camera and need some help. I was looking into polarizer filter lens and they come in different sizes, how do I know which one fits my camera? I have a Canon EOS Rebel T5i with a 18-55mm lens. Also how do I know if a Polarizer fits onto the lens of my camera?


Why worry about "danger zone" when thawing meat if I'm going to be cooking the meat immediately after?

I'm cooking my meat above 55C, mostly around 65C. I understand there are all kinds of safety measures surrounding defrosting. Using cold water and changing it every 30min or defrosting in the fridge. Making sure not to leave it on the counter or not to use warm/hot water. This is because of the danger zone; bacteria doubles every ~20 min. If I am defrosting meat in order to cook it, and I am cooking at safe temperatures, then why should I worry about how I defrost my meat?


How do I move my IPhone backup from one machine to another?

I used to sync my IPhone to my Macbook air using ITunes. All my Apps and other stuff like music and podcast were fully backed up there.  Recently I bought a new mac mini and now I want to create a full backup of my Iphone there. However after, authorizing and fully syncing I noticed that only recently installed Apps were showing up.   How can I get a full backup on the Mac Mini like how I used to have in my Macbook air ?  P/S - I do not backup my Apps on ICloud. Thanks.


Sort file "foo" and use redirection ">" to save output into the same "foo" file

i have a text file ~/foo:  a b c a b c   i use sort foo -u, and that works correctly. I can use redirection operator ">" to save output into other file (f.e.: sort foo -u > bar), but when i want to save it into original file sort foo -u > foo i get empty file as a result. Why that has happend?


The English verb "there be" in its various forms "there were," "there is," "there are," "there will be," etc. are equivalent to the Spanish verb "haber" in its forms "hubo," "hay," "habrá," etc.  Technically, when used in this way, "there" is an adverb (some say it is a noun or expletive, but I disagree). But "there" is also an adverb with an entirely different meaning and, for at least some native speakers, a different pronunciation when used to designate location: "We went there for our honeymoon."  So is "there be" classified as a phrasal verb of the form "adverb + verb"?  ADDENDUM: Does anyone know when this form arose in English?


Integral of $\int \frac{x \sin{x} \cos{x}}{(a^2 \sin^2 x + b^2 \cos^2 x)^2} dx $

Please help me to find the integral of   $$\int \frac{x \sin{x} \cos{x}}{(a^2 \sin^2 x + b^2 \cos^2 x)^2} dx $$  There is a problem in having  x in the numerator. Please guide me . Thanks in advance.


Will adding (moving) a well-visited blog to my site subdomain improve its ranking?

I have a website and a blog.  My website generates business directly, my blog indirectly. These are currently on two different domains. My website consistently ranks 2-3 for relevant search terms in my area. My blog ranks 7-9 for the same terms.  I'm considering moving (completely) my blog to a subdomain of my main site.  My question is whether you think this would have a good chance of pushing my main site up to the number one spot. I estimate I'd have tripled my traffic to the one domain in this case.  Any advice appreciated.


Question about a single event with a plural ending

Let's take the Golden Globes for example. Which of these is correct?     The Golden Globes are getting a lot of attention.   vs.     The Golden Globes is getting a lot of attention.   As a single event, my brain tells me it's the latter. The former sounds so much better though. Which is it?


How to compare the 1st column of two files and if the strings match then print "true"

I have two files, say file1 and file2.  file1:  91 | 2018-10-11 16:07:14 | bkwdv | 188.0000 | 77 | 2018-10-12 15:05:15 | wvwef | 94.0000  |   file2:  77 | 2018-10-12 15:05:15 | wvwef | 94.0000   91 | 2018-10-11 16:07:14 | bkwdv | 188.0000    I would like to compare the first column of file1 with the first column of file2.  In case the strings match (irrespective of the order, as in the given input data), it should print "success", else "exit". So, as per the given input data, it should print "success".  Please note that the number of rows in the first column could vary in either of the files, so in this case, it should exit.


This is the result I get for sudo apt-get update  W: The repository 'http://ppa.launchpad.net/t-tujikawa/ppa/ubuntu xenial Release' does not have a Release file. N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use. N: See apt-secure(8) manpage for repository creation and user configuration details. E: Failed to fetch http://ppa.launchpad.net/t-tujikawa/ppa/ubuntu/dists/xenial/main/binary-amd64/Packages  404  Not Found E: Some index files failed to download. They have been ignored, or old ones used instead.   How can I resolve this?


nslookup finds ip for a hostname in .local domain, but ping does not

I know this looks like all the other "can ping via ip but not dns" questions, but those didnt really help me at all.  Also, having hosts files in all machines is not doable as this server will eventually handle a lot of computers connecting to it.  I have a ldap+dns server set, and I want the computers on my network to authenticate on the ldap server.  The ldap part of it is working just fine and I can ssh into the ldap server with the ldap credentials just fine.  The problem comes with the client machines, the client is set to use the dns server (in this case 192.168.0.243) and if I get in the terminal and do a nslookup it finds the ldap server just fine.  fernando@desktest:~$ nslookup ldap.mynet.local Server:     192.168.0.243 Address:    192.168.0.243#53  Name:   ldap.mynet.local Address: 192.168.0.243   But when I ping it, it doesn't find the ip address. It just hangs there looking pretty till I CTRL-C it.   Of course pinging by ip address works just fine.  Here are the zone files for the dns server:  fernando@ldap:~$ cat /etc/bind/named.conf.local zone "mynet.local" {     type master;     file "/etc/bind/db.mynet.local"; };  zone "0.168.192.in-addr.arpa" {     type master;     notify no;     file "/etc/bind/db.192"; }; fernando@ldap:~$ cat /etc/bind/db.mynet.local  ; ; BIND data file for local loopback interface ; $TTL    604800 @   IN  SOA ns.mynet.local. root.mynet.local. (                   7     ; Serial              604800     ; Refresh               86400     ; Retry             2419200     ; Expire          604800 )   ; Negative Cache TTL ; @   IN  NS  ns.mynet.local. ns  IN  A   192.168.0.243 server  IN  A   192.168.0.250 desktest    IN  A   192.168.0.249 remote  IN  A   192.168.0.248 winserver   IN  A   192.168.0.247 web         IN  A   192.168.0.246 tempfs  IN  A   192.168.0.245 ldap    IN  A   192.168.0.243 antenarfb   IN  A   192.168.0.253 antenapan   IN  A   10.82.223.7 adslgvt IN  A   192.168.0.1 fernando@ldap:~$ cat /etc/bind/db.192  ; ; BIND reverse data file for local loopback interface ; $TTL    604800 @   IN  SOA mynet.local. root.mynet.local. (                   6     ; Serial              604800     ; Refresh               86400     ; Retry             2419200     ; Expire              604800 )   ; Negative Cache TTL ; @   IN  NS  ns. 1   IN  PTR ns.mynet.local. 2   IN  PTR server.mynet.local. 3   IN  PTR desktest.mynet.local. 4   IN  PTR remote.mynet.local. 5   IN  PTR winserver.mynet.local. 6   IN  PTR web.mynet.local. 7   IN  PTR tempfs.mynet.local. 8   IN  PTR ldap.mynet.local. 9   IN  PTR antenarfb.mynet.local. 10  IN  PTR antenapan.mynet.local. 11  IN  PTR adslgvt.mynet.local. fernando@ldap:~$    I am really at a loss about what to do and any help will be greatly appreciated.  ---- edit ----  before anybody asks, yes the server is running :)  root@ldap:/etc/bind# rndc status version: 9.7.0-P1 CPUs found: 1 worker threads: 1 number of zones: 16 debug level: 0 xfers running: 0 xfers deferred: 0 soa queries in progress: 0 query logging is OFF recursive clients: 0/0/1000 tcp clients: 0/100 server is up and running   ---- end edit ----


Following on from , I am trying to learn how postgresql implements the join algorithms.  So I am trying to learn about the source code of the executor precisely the file nodenestloop.c .  In the executor file I have nodenestloop.o but no binary executor file.  I am using helios eclipse to edit the source code.  I want to use gdb for debugging that file, but for that gdb needs a executor file.  I want to Debug that file using gdb and attach the postgress process file.  Could anyone help me with how to debug that file using gdb and attach a process, I know that we can find out about the pid of the process by using this command in psql, select pg_backend_pid , but how exactly are we going to give this pid to gdb.  any help or related links wwould be grateful.  Thank you


Let $G$ be a group. Prove that if $|G|=p^n$ with $p$ prime and $n \in \mathbb{N}$ then $C(G) \neq {1}$

The only thing I could think was to use the Cauchy Theorem. So I know that exists a $h \in G$ such that $o(h) = p$. Also I can consider the subgroup $H = <h>$ that all the elements have the same property and $|H|=p$.   I think that $h \in C(G)$. But if I take $g \in G$, I'm not being able to prove that $g*h*g^{-1} = h$. To take an example I thought of $\mathbb{D}_4$, where $|\mathbb{D}_4|=8=2^3$ and I can see there that $r^2 \in \mathbb{D}_4$ has order 2 and $r^2 \in C(\mathbb{D}_4)$


this is my first time to try this "Defer Parsing" thing, and I don't really have an idea how to do it.    Using PageSpeed tool, I found out that one of the reason why my page is loading too slow (currently 92/100) are the scripts. And the PageSpeed suggested that I need to Defer Parsing all those scripts.  Is there anyone that can help me with this. Thanks.


I want to match all these using 1 single regex code.   I wrote this ([a-z]{2})(\w+)?\1 but its not working   anallagmatic bassarisk abba  chorioallantois coccomyces commotive engrammatic glossoscopia hexacoralla hippogriffin inflammableness otto overattached saffarid sarraceniaceae scillipicrin tlapallan trillion unclassably unfitting unsmelled warrandice


Truth with Universal and Existential Quantifiers

New to both math.stackexchange, please let me know if I am breaking any rules with this question. Also, new to logic, so sorry if this is a stupid question. I am trying to get my head around Quantifiers. Say you have a statement that can be expressed as: $$\exists x (Rx \rightarrow \forall y Ry)$$ If the statement is written in such a way that $\forall yRy$ could be both True and False, would this statement be both true and false, and if not, how do you determine the truth of it? For example, with "there is someone who is eating such that if they are eating then everyone else is eating", $Rx$ will always be true, but will $Ry$ both true and false as we do not know if the other people are actually eating?


Having trouble understanding amps, watts, voltage, and how they all work

I read that watts is amps multiplied by voltage.  But then I read that it depends on the wattage ... what determines wattage? I thought that the outlet supplied voltage potential, and the device uses that. How do amperes, watts, etc. come into the whole big picture?  I also found that you need to know how much resistance is in a circuit to determine how many amps equals how many volts. How would one know the resistance beforehand throughout an entire circuit before figuring out wattage? I thought wattage was force.  Then I read that a volt is what "pushes" electrons, but then I read that wattage is a force equal to one joule per second.  How does it make any sense to understand that voltage is the power when wattage is considered force? There's two forces?  Assume I do not know the wattage, what is the amperes of one volt then?  I have tried books, Google searches, everything - it doesn't add up to me.  This doesn't make sense to me, and it's greatly complicated. Ironically, I've done some small electrical projects not knowing this, and it's unclear to me.  Can anyone make this clear(er) to me?


If $a|N$ and $b|N$ where $a,b$ are coprime , is it necessary that $(a \times b) |N$?

In the above statement N , a , b are natural numbers . I was wondering whether the above statement is always true . If it is always true will anyone give me a simple reason or proof for it ? Please guide me .


I simply can't figure out what the capacity of this circuit is.  I can do the math myself, I just need a hint how to create an equivalent circuit where it is obvious what is parallel and what is in series...


(Java) If and else if statements don't recognise strings

Sorry if the question doesn't make much sense, I'm very new to Java. So here's my problem: I'm making a text adventure game (very basic at the moment) and I created a string (choice1), which is equal to the answer the player gives to a question the game asks. The answer is either supposed to be north, North, south or South. When I found that no matter what I typed it said it was an invalid answer, I made the game display what choice1 was equal to when I typed my answer. I found that when I typed north, it displayed north, when I typed south, south, etc. So it had correctly picked up what I had typed, but it still said it was an invalid answer. Here is my code (including the part that displays what choice1 is equal to):  Scanner answer = new Scanner(in); String choice1 = answer.nextLine();   out.println(choice1); if (choice1 == "north" || choice1 == "North") //If the answer is North {     out.println("You start walking towards the mountains in the distance. A cold wind picks up from behind you.");   }  else if (choice1 == "south" || choice1 == "South") //If the answer is south {     out.println("You head into the forest and are quickly surrounded by trees. Patches of light dance on the floor to the whim"); }  else if (choice1 != "south" || choice1 != "South" || choice1 != "north" ||     choice1 != "North") //invalid answer  { out.println("Please enter a valid answer."); }  answer.close();


Radiation– white vs black house, hot or cool?

In my book's thermodynamics chapter, it says that an      "object that radiates heat faster also absorbs heat faster. This means   that an object that is a more efficient radiator comes to equilibrium   with its environment more quickly. With this in mind, is it better to   paint your house black or white?"   I am confused which it would be. The book says white because      "in summer, you house is cooler than the environment and white   reflects away the heat. In winter your house is warmer than the   environment and white radiates away the heat"


Left inverse implies inverse in finite dimensional algebra

Let $A$ be a finite dimensional unital algebra over a field $K$. Let $a,b \in A$ such that $ab=1$, show that $ba=1$   One way to prove this is by defining multiplication map and then using Rank nuility theorem. Is there any other way using matrices or something else?


, I'm getting the syntax coloring properly on the first section but not on the second one. I suspect that it's got to do with it being within an enumerated list. What can I do about it?  I've tried to explicitly set the language as follows but that didn't help.  <!-- language: lang-csharp -->   The tags are set correctly, of course.


Two internet connections, two routers, one network

So here is my situation. We recently got another internet connection setup here at home, which means we have two now. Each internet connection has its own router (both routers have a built in modem, if that matters). Now, on our existing local network, we have a NAS that we use for backups and such.  I am using Windows 7 or 8 on all of our PC's. The router that is used for the first of the internet connections is running DD-WRT. The router that is used for the new internet connection is a ZyXel P-2601HN-F1.   The NAS is just a PC that I built running Windows Server. The new router is not connected to the old one at the moment, so the PC's connected to the old router cannot be accessed if you are connected to the new one. What I am trying to do is to connect the two together, so that I would be able to access the PC's regardless of which router I am connected to.  The problem I am facing now, is that when you are connected to the new internet connection via the new router, you of cause don't have access to the computers and the NAS on the other network since they aren't connected in any way. How would I go about connecting the two networks so that you can access the NAS and computers no matter what router you are connected to? Would it be as simple as disabling DHCP on one of the routers and connecting the other one to it?


A problem to find a countable set with an uncountable family of subsets.

Show that there is a countable set $X$ that contains an uncountable family $Y$of subsets that if the sets $W,Z \in Y$ and $Z \cap W  \neq \varnothing $ then $W \subset Z$ or $Z \subset W$ I think that if I had two real numbers I could find two sequencies of rational numbers which converged to them and they might have some common numbers but these sequencies dont contain each other . Any ideas please ?


I have a class where kids login using guest account. I did customize this account by following  instructions.  Now my question is how can I set user groups, so that the guest account is a part of a group?  For example: For programming Arduono or running iTalc client, user has to be part of a specific group, but using guest login generates every time new user "guest-SomeRandNumber"


Unable to login to KDC server without password prompt

I am now configuring KDC client and server. My goal is to login to KDC server from KDC client using user1 without password prompt.  However, although I have below configuration, password prompt still comes us when I login from KDC client. Could someone give me advice what went wrong with my configuration?  Client and Server  KDC Client : server1.ywlocal.net (RHEL 7.3) KDC Server : server2.ywlocal.net (RHEL 7.3)   /etc/hosts  On server1.ywlocal.net :  [root@server1 ~]# cat /etc/hosts 127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4 ::1         localhost localhost.localdomain localhost6 localhost6.localdomain6  192.168.11.11 server1.ywlocal.net 192.168.11.12 server2.ywlocal.net   On server2.ywlocal.net:  [root@server2 ~]# cat /etc/hosts 127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4 ::1         localhost localhost.localdomain localhost6 localhost6.localdomain6  192.168.11.11 server1.ywlocal.net 192.168.11.12 server2.ywlocal.net   List of principals  [root@server1 ~]# kadmin -p root/admin Authenticating as principal root/admin with password. Password for root/admin@EXAMPLE.COM:  kadmin:  list_principals K/M@EXAMPLE.COM host/server1.ywlocal.net@EXAMPLE.COM kadmin/admin@EXAMPLE.COM kadmin/changepw@EXAMPLE.COM kadmin/server2.ywlocal.net@EXAMPLE.COM kiprop/server2.ywlocal.net@EXAMPLE.COM krbtgt/EXAMPLE.COM@EXAMPLE.COM root/admin@EXAMPLE.COM user1@EXAMPLE.COM   keytab file on client side created by ktadd host/server1.ywlocal.net  [root@server1 ~]# ls -ltr /etc/krb5.keytab  -rw-------. 1 root root 658 Jan  4 08:18 /etc/krb5.keytab   Client side TGT list  [user1@server1 ~]$ klist Ticket cache: KEYRING:persistent:1001:1001 Default principal: user1@EXAMPLE.COM  Valid starting       Expires              Service principal 01/04/2017 08:25:34  01/05/2017 08:25:34  krbtgt/EXAMPLE.COM@EXAMPLE.COM   ssh result  [user1@server1 ~]$ ssh server2.ywlocal.net user1@server2.ywlocal.net's password:    Client and Server Side ssh configuration  [root@server1 ~]# egrep "GSSAPIAuthentication|GSSAPIDele"     /etc/ssh/ssh_config     GSSAPIAuthentication yes   GSSAPIDelegateCredentials yes  [root@server2 ~]# egrep "GSSAPIAuthentication|KerberosAuthentication" /etc/ssh/sshd_config   KerberosAuthentication yes GSSAPIAuthentication yes   Client side krb.conf  [root@server1 ~]# cat /etc/krb5.conf # Configuration snippets may be placed in this directory as well includedir /etc/krb5.conf.d/  [logging]  default = FILE:/var/log/krb5libs.log  kdc = FILE:/var/log/krb5kdc.log  admin_server = FILE:/var/log/kadmind.log  [libdefaults]  dns_lookup_realm = false  ticket_lifetime = 24h  renew_lifetime = 7d  forwardable = true  rdns = false  default_realm = EXAMPLE.COM  default_ccache_name = KEYRING:persistent:%{uid}  [realms]  EXAMPLE.COM = {   kdc = server2.ywlocal.net   admin_server = server2.ywlocal.net   default_domain = ywlocal.net  }  [domain_realm]  .example.com = EXAMPLE.COM  example.com = EXAMPLE.COM   ssh client side debug log  debug3: authmethod_is_enabled gssapi-with-mic debug1: Next authentication method: gssapi-with-mic debug1: Unspecified GSS failure.  Minor code may provide more information Server krbtgt/YWLOCAL.NET@EXAMPLE.COM not found in Kerberos database  debug2: we sent a gssapi-with-mic packet, wait for reply


Why does the value of freed space change so quickly?

Consider the following code:  #include <stdlib.h>  int main() {     int* p = (int*)malloc(10 * sizeof(int));     printf("P = 0x%p\n", p); // prints some address     p[0] = 0;     printf("P[0] = %d\n", *p); // prints 0     free(p);     printf("P = 0x%p\n", p); // prints same address     printf("P[0] = %d", *p); // prints -572662307 always }   Why does the value of *p change so quickly after freeing up the memory?  I know it's undefined behavior to access and change freed memory. I'm just asking how come that cell always gets garbage written into it every time?


How to send data to a serial port and see any answer?

On Linux, I want to send a command string (i.e. some data) to a serial port (containing control characters), and listen to the response (which also usually might contain control characters).   How can I do this as simplest as possible on Linux? An example is appreciated!


Let $C=\begin{pmatrix}c_{11}& c_{12} \\ c_{21} & c_{22}\end{pmatrix}$ be a $2 \times 2$ matrix. Show that there exist matrices $A$ and $B$ such that $C=AB-BA$ if and only if $c_{11}+c_{22}=0$.  I could show that if such matrices exist, then the trace of the matrix $C$ is equal to zero, I did it by hand, just adding up the entries of the diagonal of the matrix $AB-BA$.  I could not prove the other implication. Suppose that $c_{11}+c_{22}=0$, then $c_{22}=-c_{11}$ so $C$ is of the form $C=\begin{pmatrix}c_{11}& c_{12} \\ c_{21} & -c_{11}\end{pmatrix}$.  I've tried to find matrices $A$ and $B$ using this condition. If $$A=\begin{pmatrix}a& b \\ c & d\end{pmatrix},B=\begin{pmatrix}e& f\\ g & h\end{pmatrix},$$ then $$AB-BA=\begin{pmatrix}bg-cf& b(h-e)+f(a-d) \\ c(e-h)+g(d-a) & cf-bg\end{pmatrix}$$  I got stuck trying to find the values of each entry, any help would be appreciated.


The follwing LaTex lines don't print out what I hope to see:  calculate $\rho_i^{t} = \| \mathcal{w}_{i}^{t} - \mathcal{w}_{i}^{t-1} \|_2$   what I get instead of the two w is that:    Can anyone help me please?  Thank you!


How to create sources.list.d directory in ubuntu 16.04

I have deleted sources.list.d directory from /etc/apt/ on my  ubuntu 16.04 system. Now, I dont know how to get that directory.


How to use clipboard data in bash script?

I very often use a simple curl command to get IP addresses details. curl ipinfo.io/111.222.333.444  Almost everytime I got the IP address in the clipboard  Is there a way to use a bash variable to automatically have the clipboard value use for IP address?  Ideally I'd like to create an alias  Alias iploc = 'curl ipinfo.io/{pbcopy}'  So then each time I copy an ip address in clipboard I can just type "iploc" in terminal and get the result.  l


Continuity of Lebesgue measure w.r.t Hausdorff distance?

If one considers the metric space $\mathcal{K}$ of all compact subsets of $\mathbb{R}^2$ endowed with the Hausdorff distance (that is $\Delta(A,B)=\inf \{ \delta: A\subset B^{\delta},B \subset A^{\delta} \}$). Is it true (and how can it be shown in that case) that the function $\mu: \mathcal{K} \to \mathbb{R}^2$ ($\mu$ is the 2-dimensional lebesgue measure) defined by $A \mapsto \mu{(A)}$ is continuous w.r.r the metric $\Delta$?


Aggregate Rating not displayed in Google search results

I have applied structured aggregate rating to my website using Schema.org but after a couple of months the 1 to 5 rich snippets are not displaying for the given set of URLs in Google.  Here is an example URL:    To me this page should be displaying the rich snippets as I have tested it using the Google Rich snippet testing tool and it has flagged no issues.  So my question is: Is the site just not authoritative enough to display rich snippets yet (I have read that Google displays rich snippets "at discretion") or is there an error in my code that is not being picked up by the tool which is hindering the display, or something else?  UPDATE: I have updated my code according to @unor recommendation which clearly states rating only. I have introduced more fresh URL's into the Google index which already have ratings but the rich snippet is still not displaying...


I'm learning c# and on many MSDN pages related to c# I came across the terms like O(n) log of O(n). for e.g.     in Remarks there is statement as" This method is an O(n) operation, where n is Count."   My Query -> I want to know what does general meaning of O(n) operation here, and what are the resources to know more about this notation?


I am new to GIS development and was wondering if there are tutorials available for development in ArcGIS 10. I have some experience writing simple scripts in python and fooling around in model builder, and I want to take the dive and make an effort to become a real programmer.  I need some more info to get a better grasp on doing some real GIS programming to make some custom tools in ArcGIS 10. Where/how did you guys learn all your GIS development skills? Any book/web site recommendations? Just an FYI I will being doing my coding in visual studio using the .net framework.


Changing precision on a column in the attribute table without losing data?

I have data in an Excel file that I want to join with a shapefile in my project. The Excel file contains values like volumes. The Excel file and the shapefile I want to join it with both contain the same property names.  The problem is, when I join the two, I get too many decimals in the attribute table. I get six, but I only want it to be one.  I tested to change the format of the cells to one decimal, and then I saved the file as *csv. But, somehow I seem to loose data in the process? It should be 42 rows that contains data in the column i am working with, but I end up with only like 10?  Another thing is that my property names contains the letters Å. Ä and Ö, perhaps this complicates things?  I read the question , but it doesn't mention the problem with the data loss.  My question was tagged with , but I didn't write what version I'm using. I use QGIS 2.2.0. Would it help to upgrade to the latest version?


I got a Schengen visa from french embassy date: from 7th February /2019 until 8th March /2019 with 15 days duration of stay my travel plan will be as following :  i will arrive in Paris on the 23rd of February by emirates airlines and i plan to leave Paris on the 7th of March and will arrive in Cairo on 8th of March and my visa valid until the 8th of March   my question : Is my travel plan on point because i don't want to overstay and leave the Schengen area n good terms and i also don't want to get into arguments with the airlines boarding staff  Thanks in advance


Qiskit: how can you use a different state for each shot in a quantum circuit?

I am trying to run a quantum circuit many times, each time using a different random state - a single qubit i.e. $|\psi\rangle= a|0\rangle + b|1\rangle$ with different $a$ and $b$. Once each qubit has gone through the circuit, I am saving the state vector of the final state, and converting this to spherical coordinates by calculating $\theta$ and $\phi$. I append each $\theta$ and $\phi$ value to a list and then plot them on a histogram (omitted below). Whilst this works, for large num_states it is very slow, so I am wondering if there is a way to use the 'shots' feature when executing the circuit, since you can write: job = execute(qc, backend, shots=1000)  I tried playing around with this but found after the initial random state was generated, it repeated the circuit with the same state for the number of shots, rather than doing a different state each time. I'd like to use the shots feature as I believe this will be much quicker since OpenMP is built into Qiskit. Any ideas on how I might be able to implement a different state each time using shots would be much appreciated:) import numpy as np from qiskit import(     QuantumCircuit,     execute,     Aer)  from math import pi  from qiskit.quantum_info import random_statevector   #----------------------------------------------------------------------# backend = Aer.get_backend('statevector_simulator')   def simulate_states(num_states):     qc = QuantumCircuit(1)      theta_vals = []     phi_vals = []          for i in range(num_states):                  random_state = random_statevector(2).data                  qc.initialize(random_state, 0)         qc.z(0)         job = execute(qc, backend)         result = job.result()         out_state = result.get_statevector()              theta, phi, alpha_r, alpha_i, beta_r, beta_i = state_coords(out_state)         theta += pi/2                  theta_vals.append(theta)         phi_vals.append(phi)              return theta_vals, phi_vals  def state_coords(statevector):     """     determines the spherical coordinates of a state on the Bloch sphere i.e. calculates \theta and \phi.     """     alpha = statevector[0]     alpha_r = alpha.real     alpha_i = alpha.imag      beta = statevector[1]     beta_r = beta.real     beta_i = beta.imag      theta = np.arcsin(2*((alpha_r*beta_r) - (alpha_i*beta_i)))     phi = 2*np.arccos(2*((alpha_r**2)+(beta_r**2))-1)             return theta, phi, alpha_r, alpha_i, beta_r, beta_i ```


Hero rescues a minor deity, granted a wish of small value; gets a girl

As a high school student just starting in science fiction, I read a short story collection in paperback that included this story – not quite a short-short, but not very long either.  I think that it was written by a familiar author, since the collection was one of those “Best Of…” anthologies.    Our hero is a sympathetic young guy trying to get ahead, in love with a beautiful neighbor, but hopeless in love.  He rescues a miniature Minor Deity (and I've forgotten the mechanism – rescued from a cat perhaps?) and gets a wish in return.  The catch is that since this is only a minor deity, the value of the wish is small – and I forget the actual value, perhaps $2.49.  He asks for help winning at the races to help get the girl – and the minor deity says sure, but the payoff can only be $2.49.  How about help rescuing her from a calamity like an earthquake?  Sure, but the total damage can only be $2.49. Other alternatives are discussed, but the value can only be $2.49. Frustrated, our hero thinks about the problem, but the Minor Deity thinks he has a solution.    Later that evening, the girl knocks on the door, he opens it to her welcoming arms, and the night passes.  The next morning, our hero finds a small clipping on the floor, an article stating the latest estimates of the total value of the elements in the human body were… $2.49.  (The whole story was building to that punch line.)


Is this correct?     The person with whom I'm doing the project should be here soon.   If it is, is with always a dative preposition (like mit in German)?


Why is the link not working if the link is created with javascript? It only works if I make the link without the html() output  Not working  $(".link").on('click', function(){     alert('Hello'); });  $("#link").html('Link');

   Working  $(".link").on('click', function(){     alert('Hello'); });  Link


How can I create a multi-color blurred background?

I have seen an image with this background. As a newbie I am unable to get this multi colored mixed background. I am able to get just two colors and that too linearly with the Blend Tool. But that doesn't look like this at all. Can some one please suggest me on how to achieve this in GIMP or in Photoshop?


I try to install MacPorts and get this  $ sudo make install make: getcwd: Permission denied shell-init: error retrieving current directory: getcwd: cannot access parent directories: Permission denied ===> making install in doc job-working-directory: error retrieving current directory: getcwd: cannot access parent directories: Permission denied chdir: error retrieving current directory: getcwd: cannot access parent directories: Permission denied make: getcwd: Permission denied /usr/bin/install -c -d -o root -g admin -m 0755 "/opt/local" shell-init: error retrieving current directory: getcwd: cannot access parent directories: Permission denied install: mkdir /opt: Permission denied make[1]: *** [install] Error 71 make: *** [install] Error 1   I am also not able to   $ sudo mkdir /opt mkdir: /opt: Permission denied   I can create the directory with   open /   and then with Finder.  I am also able to install MacPorts with the installer .pgk, but then:  sudo port install htop Error: Insufficient privileges to write to MacPorts install prefix.


Is it safe to implement a split power supply from two identical AC/DC adapters?

If I have two identical AC/DC adapters(Such as laptop adapters) can I achieve this as in the following illustration? Would it be safe?:


How to fairly select a random number for a game without trusting a third party?

Several people are playing a game with random events and require a way to produce a random number. (Such as dice rolls or a lottery.)  Can this be done such that each player has the power to be reasonably sure that the random number was fairly selected, without having to trust anyone else?  This question stems from a discussion in comments to my answer on the . I came up with a protocol but someone else spotted a flaw. This site seems more appropriate. Please feel free to make use of my answer to that question.


How do photographers programatically take photos? For example, I would like to take a photo every minute for the next day.   Can every camera be configured to take photos at regular time intervals?  What about power supply, do you use socket power supply? My old camera only has batteries and batteries clearly aren't suitable for a long period of shooting. What kind of hardware or software do you use to connect camera and all of its settings to the computer, that triggers photo capture.


Uninstall VLC , installed using Source file

I installed vlc using tar.xz file, now I want to remove it but as I have deleted the source directory from which it was installed, I am unable to uninstall it.  I have tried these commands:  apt-get remove vlc apt-get remove vlc-nox apt-get remove vlc-data sudo apt-get autoremove --purge vlc   without success


I got this error message:  An internal server error has occurred An error has occurred while processing your request. The salesforce.com support team has been notified of the problem. If you believe you have additional information that may be of help in reproducing or correcting the error, please contact Salesforce Support. Please indicate the URL of the page you were requesting, any error id shown on this page as well as any other related information. We apologize for the inconvenience. Thank you again for your patience and assistance. And thanks for using salesforce.com! Error ID: 1137932444-43272 (-1640688306)  What does it mean? What can I do about it?


I have no experience with regular expressions in java script, but I need to derive a pattern for FMLast1234@ung.edu. There only needs to be a pattern for FMLast1234 because @ung.edu needs to remain the same. I am not sure if I just do this \b[a-z][a-z][a-z][0-9] or what. Does there need to be a range for each character in the pattern? I need to check for variations of the pattern FMLast1234 not just a random assortment of characters and numbers.


Alternative to F3 for moving a window to a different workspace

Instead of pressing F3 and then dragging a window to a different workspace, how else can I move a window to diffeerent workspace?


Active directory overwriting existing computers

while adding another user with same computer name active directory i overwriting old one. Is there any way to prevent this?   I mean can i get some message or access denied when i try to add second computer with the same computer name as other that is already in active directory?


Script to open terminal and show the output of the running commands

I preface this by saying I am pretty much a complete noob when it comes to script writing.  Anyway, I am looking to create a script that opens a terminal in the GUI environment of Ubuntu, and when it does, shows the output of the other commands running in the script.   The reason for this is I am looking to take the script, throw it into the directory that runs scripts on log in and have it opening a terminal, run my normal update scripts and then keep the terminal open to allow me to continue after.  My reason is basically to just get more experience, and I figured to automate something I do every time I login.


I have a set of 10 tables and each has an extra column that I don't want. Specifically, these tables are descriptions of database tables exported by phpMyAdmin, and they all have a "MIME" column that I would like to remove. Is there a way to do this other than using string manipulation / find and replace?   I have tried setting the column to p{0in}, but the column title still remains.


how do I RDP to Ubuntu 16.04 from windows?


Altered Carbon, why is Kovacs the last Envoy?

I have started watching Altered Carbon on Netflix. I have read the books long time ago. Why is Kovacs the last Envoy?


Consider, $$ S= \sum_{k=0}^{k=\infty} \frac{ k!}{x^{k}} (-1)^k$$ now this is, $$ S = ( 1 +D+D^2 +D^3...) ( \frac{1}{x})$$ using geometeric series $$ 1+D+D^2.. = \frac{1}{1-D}$$ So, $$ S= \frac{1}{1-D} \frac{1}{x}$$ $$ S = \frac{1}{x-1}$$ Therefore , for x<1 $$ S= \sum_{k=0}^{k=\infty}(-1)^k \frac{ k!}{x^{k}}=\frac{1}{x-1}$$ Is this proof correct? Can I find an expression for l.h.s for x>1 ?


Automatically restart a Unix job if it goes down?

I have a job that I would like to "daemonize" on Unix: I want it to come up when the computer boots, and I want it to restart if it goes down.  A simple way to do this is to setup a cronjob that runs every 10 or 20 minutes. The cronjob should restart the application if it's not already running.  How do I write this last part of the script: "If the job is not currently running, then start the job"?


At what moment will matter falling into a black hole affect its size?

Does the mass of matter falling into a black hole affect the size of an event horizon the moment it passes through it, or when it has been incorporated into the singularity?


Prove $(s \to p) \to (s \to q)$ using propositional logic

I need to demonstrate $(s \to p) \lor (t \to q) \vdash (s \to q) \lor (t \to p)$ I know that, if I can do something like the following, I can succesfully demonstrate the validity of this logical sentence. However, I have no idea how to get from $s \to p$ to $s \to q$.  $(s \to p) \lor (t \to q)$ (Promise) $s \to p \ \ \ \ \ \ \ \ \ $ (Assumption) ... $s \to q$ $(s \to q) \lor (t \to p)$  and then  $t \to q \ \ \ \ \ \ \ \ \ $ (Assumption) ... $t \to p$ $(s \to q) \lor (t \to p)$  Any hint is very well appreciated. Thanks.


How can I find this font to download and use it? Please I really need it. It reads "LaTeX default" and is a serif font but I cannot find it.


Ubuntu 20.04 run ok on Lenovo ThinkPad E15 laptop?

When I get my next laptop I'm thinking of completely ditching Windows and installing Ubuntu 20.04 onto a Lenovo ThinkPad E15. Based on some googling, it looks like 20.04 will run fine on this laptop. That sound right? In particular, I'd like to confirm (if possible) that the Bluetooth stack in 20.04 will work well on this particular laptop. Any feedback appreciated. Thanks.   I’d hate to get the new laptop, install 20.04 and discover that the 20.04 Bluetooth stack does not work with this laptop. I want to connect my Sony WH-1000XM3 bluetooth headphones to the laptop. Thanks.


Okay, so I know nothing about the terminal or any of that. I'm new to this "Ubuntu" stuff. My computer was fine and I could install and download programs but my computer broke, and once fixed, now I can't download or install anything. When I try downloading from the software center, it gives me a message saying "couldn't fetch" or using old ones or something.( can't add what it says because I don't have 10 rep) if I try to use terminal, it says:  dpkg: unrecoverable fatal error, aborting: reading files list for package 'brasero-common': Input/output error E: Sub-process /usr/bin/dpkg returned an error code (2)   PLEASE can anyone help me???? I've searched all over the internet with no luck. I’m using Ubuntu 14.04 LTS. I’ve been dealing with this problem FOR MONTHS! with no solution. Please help :( (cant even install updates , it says failed to download all packages)


A typical blender panel looks like this:    We have a layout object, and we typically add stuff to it. My add-on lets user select from many garments, and for that, I need to be able to show the garment images clearly. So I can't use a button icon, since the user won't be able to see the garment properly when it is icon-size.  So I need to show an image in the panel whose size I can set. Is there a way to add an image like that to the layout of the panel?


Did Obi-Wan Kenobi prefer Luke over Leia?

Obi-Wan Kenobi's biography on starwars.com states that he chose to live on Tatooine specifically to watch Luke as if he had always intended to train Luke and not Leia. It seems that Luke had the advantage as he lived only miles away from Obi-Wan while Leia lived in an entirely different star system.  Like some say, it could just be a coincidence that Obi-Wan happened to live on the same planet as Luke, but Yoda got an entire planet to himself. Surely, Obi-Wan could find a better planet to hide out than Tatooine. Preferably, a planet between Tatooine and Alderaan, so Luke and Leia could have an equal chance of crossing paths with him.  All signs point to the fact that Obi-Wan must have preferred Luke in some way when he decided to live on Tatooine and not bother with Leia on Alderaan. Maybe Obi-Wan could sense the Force was stronger with Luke at birth (they were fraternal twins and not identical twins), and that is why he did not care as much about Leia. The fact that he allowed Leia to be adopted by such a high-profile family as the Organas but took Luke to a remote planet such as Tatooine where he would be under the protection of a Jedi Knight further proves my point.  To me it seems like Luke was chosen to become a Jedi from the start, but what do you think? Was the fact that Obi-Wan chose to live on Tatooine and watch over Luke as opposed to Leia on Alderaan proof that he preferred Luke for some reason, or is it just a painful coincidence?  EDIT: Was Luke really only trained to go with Obi-Wan to Alderaan, or was that just an excuse to commence Luke's training because it is really hard to believe that Luke needed the Force just to travel in a space ship to Alderaan.


Why is this proposition provable and its converse not?

I found this proposition and don't see exactly as to why it is true and even more so, why the converse is false:  Proposition 1. The equivalence between the proposition $z \in D$ and the proposition $(\exists x \in D)x = z$ is provable from the definitory equations of the existential quantifier and of the equality relation. If $D = \{t_{1},t_{2},...t_{n}\}$, the sequent $z = t_{1} \vee z = t_{2} \vee z \vee ... z = t_{n}  \vdash z \in D$ is provable from the definition of the additive disjunction $\vee$.  The converse sequent $z \in D \vdash z = t_{1} \vee z = t_{2} \vee ... z = t_{n}$ is not provable.  The author goes on to say:  "We adopt the intuitionistic interpretation of disjunction. With respect to it, one can characterize a particular class of finite sets"  On the first part of the proposition, well I am not sure what the point is as if we take an element z in D, then we could just call this element x and hence this x = z.  Is there something more to this?  On the second part of Proposition 1 since $z = \text{ some } t \in D$ since t is in the set of axioms and $t = z$, then $t \vdash z$ as z is derivable from t.  For the converse if $z \in D$ then why wouldn't z = some $t \in D$?  Is this because of the Incompleteness theorem?  That perhaps there D as a set of axioms has some consequence which can not be proven by the set of axioms in D?  Or perhaps I am way off here.  Any ideas?  Thanks,  Brian


Could I get decent underwater photos from a waterproof compact camera or is it worth buying a housing?

I'm going travel next month and been told that it's going to be great snorkeling waters where I'm going. So I thought it would be fun to take some underwater photos, which I have never done before.  I was originally planing to buy a underwater housing for my  but the only one I can find is from  and it's rather expensive.  Could I get decent photos from a waterproof compact camera or is it worth buying the housing?  Any camera recommendations?


When I read articles, FPGA comes with a specification-nm. For example, Xilinx 28nm Virtex 7 or 20nm UltraScale FPGAs. What does -nm means in FPGA?


Browser close event not working with chrome,firefox

I just want to override the browser closing message so i tried to do the following:  <script type="text/javascript">  window.onbeforeunload = closeEditorWarning;  function closeEditorWarning(){ return 'AAAAAAA' }  </script>   but unfortunately it doesn't work! what should i do to make it work?


.NET WinForms - application which is not dependent to .NET Framework?

Is it possible to develop a WinForms application which when deployed (of course on Windows) will not be dependent to .NET Framework? And How?  Okay, put it this way, I want all the dll's and stuffs to be included in my application, so when installed in a machine, the users don't have to install .NET Framework, something like that. Is it possible?


I have this code in my python script  class Class(object):     client_id = ''      @classmethod     def get_client_id(cls):         return cls.client_id   class Service(object):      @staticmethod     def get_class():         cls_obj = Class()         cls_obj.client_id = 'this is client id'         return cls_obj  print(Service.get_class().get_client_id())   but when i run the python script, it displays empty string and not the 'this is client id'. please help


How can I solve the localhost/phpmyadmin

if i browse localhost/visiondms it shows, Fatal error: require_once(): Failed opening required 'C:\xampp\htdocs\visiondms/wp-admin.php' (include_path='C:\xampp\php\PEAR') in C:\xampp\htdocs\visiondms\index.php on line 10 Please tell my what can i do?


How to prove $f$ is in the span of $f_{1,\cdots, n}$?

Suppose $f, f_{1,\cdots,n}\in X^*$ where $X$ is a normed vector space. How to show that, if $\cap Ker f_i \subset Ker f$, then $f$ is a linear combination of $f_{1,\cdots,n}$?  I'm at a loss even for the classical linear algebra cases (where $X$ is a finite dimensional Euclidean spade with $\ell^2$ norm, so really don't know how to proceed for the more general cases.    EDIT  It seems I might want to relax the conditions a little here. So let's now assume $X$ is a Banach space.    EDIT The Banach space assumption can be dropped. Any normed vector space is okay.


Show that if $p>2 $ is prime, then $8$ divides $p^2 -1$.

I have started it like this If $p>2$, then $p= 2k+1$ , $p^2= 4k^2 +4k+1$, $p^2 -1 = 4k(k+1)$ , But I can't get how to make it divisible by $8$.


Does anyone actually use and benefit from transparent huge pages?

I've been struggling with transparent huge pages performance issues of late, and noticed many database systems recommend turning it off. I am talking Oracle, Postgresql, MySQL, Cassandra, NuoDB, Redis, Hadoop, and more.  For examples:   Peter Zaitsev (2014-07-23). .  Percona. Michele Casey (2013-09-17). .  Oracle. Adam Abrevaya and Oleg Levin (2014-05-15).  .  NuoDB DevCentre.   So I am wondering: what kinds of workload do benefit from this feature?


Is there a way to log all commands run on bash together with timestamp?

Is there a way to create a kind of audit trail of what commands were run in bash together with timestamp? I know history logs all commands. But it doesn't add a timestamp to the history.


When installing I'm given the option of encrypting my home folder -- what does this do?

Does encrypting my home folder make my computer more secure? Do I have to enter my password more if my home folder is encrypted? What else should I know about encrypting my home folder?


Don't show how to format code when I'm not on a programming site

Instructions on how to format code are the first thing you see under "How to Format" when , which is great, except when you're on a site that isn't about programming:     ► create code fences with backticks ` or tildes ~  ``` like so ```       ► add language identifier to highlight code      ```python def function(foo):     print(foo) ```    Later on in the sidebar you're shown more instructions for code formatting:     ► indent code by 4 spaces      ► backtick escapes `like _so_`   Can these be removed, or at least moved down to the very bottom of the list on non-programming sites?  isn't for programming languages, so this needs to be fixed.  Maybe the rest of the list should be reordered too in order of importance (which would have link formatting coming somewhere closer to the top of the list).


My folders became hidden system files and access denied

I have an external HDD which suddenly seems infected and one of my folders which contain my photos changed to something like this:    One of Super User guys suggests that I install an Ubuntu and try to scan and change permissions, but I am not an Ubuntu expert, and believe me if my problem solve I will switch to it ('cause all I do is writing and taking photos. I am tired of malware, etc.)   Now I have Ubuntu and Fedora installed (after a long read through guides); both of them show infected folder as empty (in Windows 7 I see this strange folders, as you can )


Why can't we use the word information in the plural form? "Give me all the informations you've got", even if it's wrong, sounds more beautiful to my non-native ear than "give me all the information you've got", and I don't know why.  Edit: This is not a duplicate question since I know that information is a mass noun; what I am asking is, why can't it be in plural like some other mass nouns can? Why is it like that when it seems more correct with s at the end?


How to run custom command by pressing a key

I have cmus music player installed and I really like it.  I need to run a command by pressing a key, for example CTRL+F so it will open browser and search a lyrics for currently playing song.  The command might be something like:  /usr/bin/google-chrome --new-tab http://search.azlyrics.com/search.php?q=[name-of-the-song]  Is it possible and if so where and how can I define such command ?  UPDATE:  Sorry for not being clear enough. This has nothing to do with global system keyboard shortcuts (as I know how to made them). Let me explain:  I am running cmus music player and within it I am selecting a song to play and play it. Then I want to run an "external command" for this song. By running some key shortcut (while this song is played) I want to run a command that will search lyrics for this song.


def main():    w = [[0]*3] * 3    print("original w", w)    w[0][2] = 2    print("new w:",w)     k = [[0,0,0],[0,0,0],[0,0,0]]    k[0][2] = 2    print("new k",k)   output is:  original w [[0, 0, 0], [0, 0, 0], [0, 0, 0]]  new w: [[0, 0, 2], [0, 0, 2], [0, 0, 2]]  new k: [[0, 0, 2], [0, 0, 0], [0, 0, 0]]   Question is why w[0][2] =2 make w change all second index not only w[0][2] but also w[1][2] and w[2][2] ? I want to change w like k ( only change [0][2])  I don't know the difference between the two lists. Thank you for letting me know my errors! Thanks!


When will students be taken into account?

As student, I recently asked myself - and other mates did - why Stack Overflow had no special diet adapted to students, more indulgent than with developers. Indeed, we noticed that our questions were frequently downvoted or did not receive enough attention. I don't find it normal that a beginner does not really have the same chance than an experimented developer, as its reputation tends to stay low  Thus, although I perfectly understand that Stack should remain something for "professional developers" and not a MOOC-provider, I think that it should be fine to give a special status to students to avoid them being discouraged to ask questions that could seem obvious.  So I would suggest a scholarship proof from the university or school to avoid derives. It would witness of open-mindness


How can a computer with dynamic IP work as a webserver?

How can a computer with dynamic IP work as a WebServer?


Evaluating limit making it $\frac{\infty}{\infty}$ and using L'Hopital Rule

Let $P(x)=x^n+\displaystyle\sum\limits_{k=0}^{n-1}a_kx^k$. Find $$ \lim_{x \to +\infty} ([P(x)]^{1/n}-x) $$  I know that in order to solve this problem I need to multiply it by something that will make it $\frac{\infty}{\infty}$ and then use L'Hopital Rule. I also know that the answer should be $1/n$ if I am not mistaken. I have tried multiplying the expression by $\frac{e^x}{e^x}$ and then using L'H. Rule but with not much success. Any suggestions on how I should proceed? Thank you for the help.


sudo dpkg -i code_1.20.0-1518023506_amd64.deb [sudo] password for wolfubuntu:  (Reading database ... 189470 files and directories currently installed.) Preparing to unpack code_1.20.0-1518023506_amd64.deb ... Unpacking code (1.20.0-1518023506) over (1.20.0-1518023506) ... dpkg: dependency problems prevent configuration of code:  code depends on libgconf-2-4; however:   Package libgconf-2-4 is not installed.  dpkg: error processing package code (--install):  dependency problems - leaving unconfigured Processing triggers for gnome-menus (3.13.3-6ubuntu5) ... Processing triggers for desktop-file-utils (0.23-1ubuntu3) ... Processing triggers for mime-support (3.60ubuntu1) ... Errors were encountered while processing:  code


Python equivalent to MATLAB's dynamic array initialization

In MATLAB, I can create an array and assign values to it dynamically without mentioning the size of the array while its creation.  I'm new to MATLAB, the following show how I create an array and assign values to it in MATLAB.  >> a=[] a =       []  >> a(2,2) = 55 a =       0   0      0   55   We can write a function in Python to do this but I want to know that is there any equivalent procedure to MATLAB functionality of assigning values to array dynamically in Python or in Numpy?


How to count for a certain amount of seconds before breaking from program

if pygame.sprite.collide_rect(ship,missile) == True:     ship.image = pygame.image.load("lose.jpg")     ship.image = ship.image.convert()     ship.rect = ship.image.get_rect()     break   How do I make it so there is a few second wait while it shows 'lose.jpg' and then breaks and exits the program?


I am using my early 2015 MacBook Pro as a desktop by connecting it to an external display, thus, it needs to be plugged in to a charger all the time.  Does charging my early 2015 MacBook Pro all the time damage the battery? Is it a bad practice?


Windows Active Directory naming best practices?

This is a  about Active Directory domain naming.   After experimenting with Windows domains and domain controllers in a virtual environment, I've realized that having an active directory domain named identically to a DNS domain is bad idea (Meaning that having example.com as an Active Directory name is no good when we have the example.com domain name registered for use as our website).   , but I'm still not sure about what other rules there are around naming Active Directory domains.  Are there any best practices on what an Active Directory name should or shouldn't be?


How can I import Facebook events into my Google calendar?

I get a lot of invitations via Facebook, but I keep track of my schedule with Google calendar. Is there any way to automatically import or sync my Facebook events to my Google calendar?


Stochastic Integral martingale if no $dt$ term?

There is a proposition in my book that  For a process $M_t$ to be a martingale, it is necessary that its stochastic differential $dM_t$ has no $dt$ term.   Why is this exactly? My guess is that it implies there is no change with respect to time $t$. This is speculation, and is the story told with the 2nd property given regarding conditional expectation.  A martingale only requires that: $$1. \space \forall t, E \|M_t \| < \infty$$ and $$2. \space \forall t,s>0, \space E[M_{t+s}|\mathcal{F}_t] = M_t$$


Shortcut key to remove formatting after pasting?

I'm copying and pasting a lot of citations, and the formatting comes out of my browser, into my document.  I use the "dark reader" extension in Chrome so all of my text is wrongly formatted when it is pasted into my word document.  How do I remove formatting by pressing a hotkey?  This seems to be working in 2013 - 2020 (please let me know if you've tested other versions).