I am trying to understand the most significant jewel in mathematics - the Euler's formula. But first I try to re-catch my understanding of exponent function.  At the very beginning, exponent is used as a shorthand notion of multiplying several identical number together. For example, $5*5*5$ is noted as $5^3$. In this context, the exponent can only be $N$.  Then the exponent extends naturally to $0$, negative number, and fractions. These are easy to understand with just a little bit of reasoning. Thus the exponent extends to $Q$  Then it came to irrational number. I don't quite understand what an irrational exponent means? For example, how do we calculate the $5^{\sqrt{2}}$? Do we first get an approximate value of $\sqrt{2}$, say $1.414$. Then convert it to $\frac{1414}{1000}$. And then multiply 5 for 1414 times and then get the $1000^{th}$ root of the result?   ADD 1  Thanks to the replies so far.   In  recommended by several comments, a function definition is mentioned as below:  $$ ln(x) = \int_1^x \frac{1}{t}\,\mathrm{d}t $$  And its inverse function is intentionally written like this:  $$ exp(x) $$  And it implies this is the logarithms function because it abides by the laws of logarithms.   I guess by the laws of logarithms that thread means something like this:  $$ f(x_1*x_2)=f(x_1)+f(x_2) $$  But that doesn't necessarily mean the function $f$ is the logarithms function. I can think of several function definitions satisfying the above law.  So what if we don't explicitly name the function as $ln(x)$ but write it like this:  $$ g(x) = \int_1^x \frac{1}{t}\,\mathrm{d}t $$  And its reverse as this:  $$ g^{-1}(x) $$  How can we tell they are still the logarithm/exponent function as we know them?


how to prove $\mathbb Z_n$ has divisors of zero if and only if $n$ is not prime

A non-zero number $a \in \mathbb Z_n$ is called a divisor of zero if there is a non-zero number $b \in \mathbb Z_n$ such that $ab\equiv 0\pmod n.$  How can I prove $\mathbb Z_n$ has divisors of zero if and only if $n$ is not prime.  I filled out the addition and multiplication tables for modulo 6 and 7 and tried to find out the relation, and it's definitely true. I know I need to prove it in both directions since it is an 'iff' question. But I still don't get it.


Can we set `Cronjob` to run on Particular date once a year?

Requirement: I have shell script for updating security patches on Linux servers which has to run on maintenance timings/windows. What we have tried as suggested here: We are trying to edit /etc/crontab file as below: 30 13 16 * * root [[ $(date "+%Y") == 2020 ]] && /path/to/shellscript  Issues: We are not able to execute above cron job: o/p in logs: CROND[24576]: (root) CMD ([[ $(date "+)  I am sure I am missing something in syntax of the cronjob but not sure what is that. Please help me in resolving the issue.


Too much flags waiting for review: should I stop flagging a moment?

Please do not flag this question as a duplicate of this one:  This is not a general question, but more a localized question that probably should be closed as soon as replied.  These days, I sent a lot of flag. I noticed that more I send flag, more I can send flag. I can currently flag 62 times per day and all the flags all can't be reviewed quickly. So the number of flag waiting for review is growing, growing, and growing.  I have currently more than a hundred flags waiting for review and I don't know if it is a problem. So please just let me know If I should stop a moment?   Note: my goal is just to participate to maintain quality of the site. It is not to break the machine. ;-)


"Is" or "are" when linking two subjects with different plurality

How should this sentence be written?  The crux of the problem is the two trees in the way. The crux of the problem are the two trees in the way. The cruxes of the problem are the two trees in the way.  The third seems grammatically correct, but also the most awkward.


Is it acceptable to post a duplicate or very similar answer to non-identical duplicate questions on different SE sites?

Typically, this would involve duplicate questions. I searched SO-Meta to see if this question was already answered, and I found a few, but they all related to answering questions duplicated on the same SE site.  In this case, I'm talking about duplicate or near duplicate questions found on different SE sites. And to be clear, I'm not talking about cases where the same user might cross post the same question on multiple SE sites. I mean 2 questions by different users and not obviously copy-pasted from one to the other, but still essentially duplicates.  I don't have any specific examples at hand, but I've seen questions on Stack Overflow or Super User or Server Fault or Programmers.SE, and seen a duplicate or near duplicate on one of the other sites. I'm talking duplicate to the extent that sometimes they could both be answered with the same answer.  So my question is, if I can answer the question, is it OK to post the same or nearly same answer to the questions on both sites, or should I make significant efforts to hide the fact that the answers are the same?


Changing number of rows when importing table

I'm currently importing a table with about 17 million rows in MySQL. What catches my attention is, the number of row seems to be fluctuate.   I used the command show table status while my importing process was running. One time, I got 1.5 million of rows, then I ran that command again and got lower than 1.5 million. How is that possible?


How can I trigger a component condition only on uninstall, but not on an upgrade?

I want to remove the file File.txt only on uninstall, but not on an upgrade. We are using the <MajorUpgrade ...> element for upgrades.  When we use the following Component, the File will be removed every time, also on an upgrade:  <Component Id="RemoveFileComponent" Transitive="yes"  Directory="BIN" Guid="MY-GUID-HERE">   <Condition>REMOVE=ALL AND NOT UPGRADINGPRODUCTCODE</Condition>   <RemoveFile Id="RemoveTextFile" Name="File.txt" Directory="BIN" On="uninstall" /> </Component>   The attribute <RemoveFile ... On="uninstall" /> changes nothing on this behaviour. The file will be consequently deleted when doing an upgrade.  UPDATE: In an <CustomAction>REMOVE=ALL AND NOT UPGRADINGPRODUCTCODE</CustomAction> the condition works correctly on an update or uninstall, but the same condition does not work correctly in and component condition: <Condition>REMOVE=ALL AND NOT UPGRADINGPRODUCTCODE</Condition>. I am not interested to use an <CustomAction> in combination of an assembly or command line statement as and unstable workaround. I am not requesting for a solution using a <CustomAction> described here:  I want to get work it with a component condition, described in my question.


I've seen this question for older versions of the Mac mini, but I'm struggling to find an answer for the Mac mini 2018.  I want to connect 3 identical monitors (22inch 1080p). I'm currently able to connect 2 monitors using HDMI-Thunderbolt 3 cables, but I'm unable to get the 3rd monitor to detect a signal. I have a 3rd HDMI-Thunderbolt 3 cable, and I also have a VGA to HDMI adapter I can use as well.  If I plug the VGA-HDMI cable into he HDMI port on the Mini, the two functioning monitors begin to flicker. The third monitor is still not detecting a signal.   The monitor is a 1920x1080, 75 Hz  Has anyone successfully configured a 2018 Mac Mini to 3 monitors using one of these configurations?  Thanks!


Use integral test to show that Gaussian Integral $\int_{-\infty}^{\infty} e^{-x^2} \ dx$ converges?

There's a question in my book (it's a school-specific textbook) saying:  Use the integral test to show $$\int_{-\infty}^{\infty} e^{-x^2} \ dx$$ (the Gaussian Integral) converges.  The integral test says if the integral converges, so does the series. But I have no idea how to represent this as a series, do I need to?   I'm not looking to evaluate it - I've read about it online - but how do I use the integral test here?  Thanks


I have a website build for two groups both groups are working on a different domain but this domain points to the same website en show partly the same and partly different content. Is this going to be seen as duplicate content?  My set-up:  One Drupal (CMS) Installation. I have two urls group1.com and group2.com when group1.com the end up on a homepage showing different information then going to group1.com. This is all fine. But on both sites there are articles.  group 1 has access to:   group1.com/article-001 group1.com/article-002 group1.com/article-005 group1.com/article-006 group1.com/article-007 group1.com/article-009   group 2 has access to:   group2.com/article-001 group2.com/article-002 group2.com/article-003 group2.com/article-004 group2.com/article-005 group2.com/article-007 group2.com/article-008   So article-001, article-002, article-005 and article-007 are the same, and because of the different domain I think the are seen as duplicates. How to prevent negative impact because of this?  Is this as simple as adding a canonical url saying group1.com or group2.com is the original?


What is a tandem breaker (aka duplex, cheater, twin, double-stuff, etc.)?

I keep hearing about tandem breakers, and how they won't work with 240V loads and how they should never be used for a multi-wire branch circuit.  Aside from those issues...  What is a tandem breaker?     (note: they can be thrown independently).


What is difference between User space and Kernel space?

Is Kernel space used when Kernel is executing on the behalf of the user program i.e. System Call? Or is it the address space for all the Kernel threads (for example scheduler)?  If it is the first one, than does it mean that normal user program cannot have more than 3GB of memory (if the division is 3GB + 1GB)? Also, in that case how can kernel use High Memory, because to what virtual memory address will the pages from high memory be mapped to, as 1GB of kernel space will be logically mapped?


I have a basic question on the definition of "population" in statistics.   Use this as example: the height of everyone in U.S.  In my study of probability and statistics course long time ago majoring engineering, the population means all of the heights of all people in U.S.  Now I'm taking courses to get certification as high school math teacher. In my math education class, the professor says I'm wrong. She wrote:  You say "population refers to the data being studied, which is the height of each student. The “population” is a collection of the heights of the students."  This is not quite correct - the heights are considered the variable of the population/observational units/individuals being studied. The population is not the data values.  I talked to my professor again, and am sure that she says that in this case the population is all people.  I checked on internet, and saw both ways (mine and my professor's. I hope to get some clarity and answer here.


How to add debian "testing" repository to apt-get

I had difficulty searching for this answer on google and debian documentation!  The FAQ page wasnt very clear either. I mean it wasnt 100% idiot-proof clear.


multiple definition error including c++ header file with inline code from multiple sources

I have a c++ header file containing a class. I want to use this class in several projects, bu I don't want to create a separate library for it, so I'm putting both methods declarations and definitions in the header file:     // example.h #ifndef EXAMPLE_H_ #define EXAMPLE_H_ namespace test_ns{  class TestClass{ public:     void testMethod(); };  void TestClass::testMethod(){     // some code here... }  } // end namespace test_ns #endif   If inside the same project I include this header from more than one cpp file, I get an error saying "multiple definition of test_ns::TestClass::testMethod()", while if I put the method definition inside the class body this does not happen:  // example.h #ifndef EXAMPLE_H_ #define EXAMPLE_H_ namespace test_ns{  class TestClass{ public:     void testMethod(){         // some code here...     } };  } // end namespace test_ns #endif   Since the class is defined inside a namespace, shouldn't the two forms be equivalent? Why is the method considered to be defined twice in the first case?


Why the electric field inside a conductor is zero?

In electromagnetism books, such as Griffiths or the like, when they talk about the properties of conductors in case of electrostatics they say that the electric field inside a conductor is zero.


Proving some property of a Formal Logic Language

I am stuck at this problem:    Let $\Sigma = \{\lnot,\lor,\land,\rightarrow,\leftrightarrow,(,),P_1,...,P_n\}$  be an alphabet.  Now let's define the set of logical expressions $\mathscr{L} \subseteq \Sigma^\ast$ recursively as follows:  Rule #1: For each $i\in\{1,2,...,n\}$, $P_i\in \mathscr{L}$  Rule #2: For each $\phi \in \mathscr{L}$, $\lnot \phi \in \mathscr{L}$  Rule #3: For each $\phi,\psi \in \mathscr{L}$ and $@\in\{\lor,\land,\rightarrow,\leftrightarrow\}$, $(\phi @ \psi)\in\mathscr{L}$  No strings other than those derived from Rules #1, #2 and #3 are in $\mathscr{L}$.    Prove that for all $\phi,\phi' \in \mathscr{L}$, $\psi,\psi'\in\Sigma^\ast$ and $@\in\{\lor,\land,\rightarrow,\leftrightarrow\}$, If $(\phi @\psi)=(\phi' @\psi')$ Then it must be the case that $\phi = \phi'$ and $\psi = \psi'$.    I tried to prove it using structural induction and ordinary induction, but I wasn't  able to prove it.  What we need to show is that the @ in the strings $(\phi @\psi)$ and  $(\phi' @\psi')$ lies at the same index position, and then we  will get immediately that $\phi = \phi'$ and $\psi = \psi'$ by definition of string equality.  Thanks for any help.


Email links don't open the Stack Exchange Android app

EDIT: I was offline for the last few hours, so I couldn't look at the other question of which this one here was a duplicate.  It is not a duplicate, because the linked question mentions Stack Exchange links explicitly. The problem I face has to do with the fact, that links in Stack Exchange mailings are not exactly what the Stack Exchange app would expect an Stack Exchange link to look like. I would not even call this a Stack Exchange link, since it doesn't lead to a site within the Stack Exchange network you would normally link to.  I guess they are some sort of click-tracker link, or something like that, but that's not the important part, here. Here's what one of the links looks like:  http://sg-links.stackoverflow.email/wf/click?upn=pDzA4vSaPmKy14MynsLvnZrGP7ewVN5UzFsPjLNsxf37lv5vH-2FL7YDbAQsAtLugYNp-2BJiZcu65iHCdCmWwcPykni0h3G-2BW3a5DJQvmvpqO5YYk0exrZkOZd357pJfsQtX23gZixSuNBvjUBdJW0S-2FYJxGOjASUTK1FgJWcFKhWk-3D_AOPg-2F-2BQL2BN1Z1adM2aHoJZemfJJPhUU1r33PmBub3XkdttNEsj9eAI3iXegmVDgNR1kPnNqBKQmCk2dsyn9uQ5g2T8fxWFcEgLgWVEljU9HeN8V3E9CiWFKeHBN3AsBll3Ol5ooWPcw1zAzDtJBxhi9y23WRvLODAGnxo8GjN2JvPOgbDchbKP4fGLU5bdnPtYYvcBBziE3leh3q-2FXLhm6oVzcczCqFM3tXWWWXJuY-3D   If this question is not attracting any more attention and doesn't loose the dupe tag, I guess I will have waited too long with my edit. In this case, I will delete it and submit a "new" question.    Yeah, so, the title says it. Because the links in the emails are not specifically from Stack Exchange, the app doesn't recognize it as something it's supposed to want to open and each link I tap in an email just opens my mobile browser.   App Version: 1.0.95 Device Manufacturer: Samsung Device Model: SM-A520F   OS Version: 8.0.0 (A520FXXU8CSC1)


Why am I getting error 1064 when creating a table?

Here is my DDL statement:  create table if not exists 'fmrecruit'.'resource_type'(   'ID' bigint not null auto_increment,   'type' bigint null,   'first_name' varchar(30) not null,   'middle_name' varchar(30) null,   'last_name' varchar(30) null,   'org_name' varchar(45) null,   'notes' varchar(256) null,   'primary_skills' varchar(256) not null,   'seconadary_skills' varchar(256) null,   'created_by' varchar(25) not null,   'created_date' timestamp not null,   'updated_by' varchar(25) null,   'updated_date' timestamp null,   primary key('ID'),   index resource_type_fk_idx('type' asc),   constraint resource_type_fk foreign key('type') refrences fmrecruit.resource_type('ID')   on delete no action   on update no action)   engine=innodb;


Easy way to switch default sound output device

I want an easier way to change my default sound device from my sound card to my usb headset.  Currently it takes a very precise right click, a left click, another right click, and two more left clicks.   Ideally i could just have it swap with a shortcut key. (it was a little easier in XP but not by much.)   A software solution is preferred, but I am open to suggestions that use hardware.   I am running Windows 7 currently.


Show that the $\max{ \{ x,y \} }= \frac{x+y+|x-y|}{2}$.

Show that the $\max{ \{ x,y \} }= \dfrac{x+y+|x-y|}{2}$.   I do not understand how to go about completing this problem or even where to start.


How to make a reference to a cell of another sheet, when the sheet name is the value of a cell?

In excel 2007, I have a formula in a cell like the following:  =COUNTIFS('2008-10-31'!$C:$C;">="&'$A7)   Now I want to make the name of the sheet ('2008-10-31') be dependent on the value of some cell (say A1). Something like:   =COUNTIFS(A1!$C:$C;">="&'$A7) // error   Is there is way to do this? Or do I have to write a VBA-Macro for it?


Custom label and reference equations in numcases

I have labelled and tagged a piece-wise function using numcases. However, when I reference the equation later, it is not displaying the right tag in the text. \documentclass[11pt,fleqn]{article} \usepackage{fontspec} \setmainfont{Arial} \usepackage{titlesec} \usepackage{geometry} \geometry{a4paper,left=3cm,right=2cm,bottom=2cm,top=2cm} \usepackage[fleqn]{amsmath} \usepackage{gensymb} \usepackage{amssymb} \usepackage{hyperref} \usepackage{cases}{} \setlength{\mathindent}{0pt}  \begin{document}   \begin{numcases}{f(x,y) =}         x^2 + (y-k)^2 = k^2 &$; 0 < x < p$  \tag{4.3} \label{eqn:4.3}  \\          (b_2-q)(x-a_2) + (p-a_2)(y-b_2) = 0 &$;x \geqslant p$  \tag{4.4} \label{eqn:4.4}        \end{numcases}\\       \noindent On solving equations \ref{eqn:4.3} and \ref{eqn:4.4}  \end{document}  The output is:  How can the problem be solved?


How to check the apt list of repository?

I have a list of packages from my repository say some_repo,   Few packages in that has two versions and when I run my script to fetch the packages from repository the two versions of package is being downloaded,  I just want the installed version of the packages,   How do i get it?  Eg:   Package, Version          xyz          1.2.3          xyz          1.2.3.4    For Package xyz Version 1.2.3.4 is been installed, I just want the installed version of those packages which has two or more version


Regex for quoted string with escaping quotes

How do I get the substring " It's big \"problem  " using a regular expression?  s = ' function(){  return " It\'s big \"problem  ";  }';


Is there a clean way to prevent windows.h from creating a near & far macro?

Deep down in WinDef.h there's this relic from the segmented memory era:  #define far #define near   This obviously causes problems if you attempt to use near or far as variable names.  Any clean workarounds? Other then renaming my variables?


How to escape an apostrophe (') from an xml fed string value

I am taking an XML to load into a database, but the feed comes fully loaded with apostrophes! What would be the best way to capture these as they are making the whole system go whoopy and not input as intended?  For example, instead of Wolverhampton, I am given W'Hampton, which then goes into the table as W, nightmare!   I have spent quite some time trying to work this out, look on Google and on here with no luck so anyone who can help me really is the best!


Date is not being read by JFormattedTextField? Gives `java.lang.NullPointerException`

I am designing a staff data manager which will allow the users to add, edit and view the staff details.  In the code I  have a JFormattedTextField defined as follows.   SimpleDateFormat dateDOB = new SimpleDateFormat("dd/MM/yyyy");  JFormattedTextField DOBBX = new JFormattedTextField(dateDOB);   When I want to edit the staff data, I load the date to the JFormattedTextField as follows:  DOBBX.setText(""+retrievedStaff.getDOB());   After editing if I save the data, the value for DOB is null and I get a java.lang.NullPointerException. This only happens if I leave the value for DOB unedited. If I make changes to DOB or enter it again then DOB value is correctly saved.  Also if I add a new staff and then try to edit the staff data without closing the program, the date is properly saved to the binary file with no nullpointer error.  How do I fix this?   (I have no idea how to provide an MCVE for this as my code is quite long and consists of many classes)  Before saving the date to binary file I use the following method to convert it to a string:  public String getDOB() {     SimpleDateFormat df = new SimpleDateFormat("dd/MM/yyyy");     try{     String textDate = df.format((DOB));     return textDate;     }catch(Exception e){e.printStackTrace();}     return null;  }   In the StackTrace it is mentioned that the error is produced by this part of the code:  String textDate = df.format((DOB));


What is the word for 'not good at expressing words / thoughts / emotions in person'?

Kind of like:  not good at expressing oneself


I'm writing a short tabular CV that I have to add to my thesis. I thought a quick way would be to use a table for that purpose:  \begin{tabular}{ll} 2009-present           & very long text 1, very long text 2, very long text 3 , very long text 4, very long text 5, very long text 6, very long text 7, very long text 8, very long text 9, very long text 10\\ 2009  & Masters\\ 2006  & Bachelors\\ \end{tabular}   Unfortunately, LaTeX does not break the lines at the spaces. The only solutions I found so far, are   "adding additional rows to the table" "use fixed table size + \newline".   Manually adjusting texts is not very efficient.  Is there also a way to automate this (e.g. by define a cell/column as "text-cell/column")?  \begin{tabular}{lp{12cm}} 2009-present           & very long text 1, very long text 2, very long text 3 , very long text 4, very long text 5, very long text 6, very long text 7, very long text 8, very long text 9, very long text 10\\ 2009  & Masters\\ 2006  & Bachelors\\ \end{tabular}   Could be a solution, but the right column does not automatically reach the right "border" of the page.


What regular Expression match all international Mobile numbers

I would like to validate mobile number field. I have tried many regular expression based on my requirement  Matching cases   (923)(423)(34455) 945 443 4442  919774744323 +92 332 45 666 9144565 91-877-3655   I need a regular expression based on my matching cases.


An operator $\hat{Q}(t)$ can be  written as $\hat{Q}(t)= e^{iHt} \hat{Q(0)} e^{-iHt}$ in Heisenberg picture.  Let us choose $\hat{Q(0)} = |{m(0)}\rangle \langle{m(0)}|$. Then $e^{iHt} \hat{Q(0)} e^{-iHt} = |{m(-t)}\rangle \langle{m(-t)}| = \hat{Q}(-t) $  and not $\hat{Q}(t)$. While as the reversing the order of evolution operators gives  $e^{-iHt} \hat{Q(0)} e^{iHt} = |{m(t)}\rangle \langle{m(t)}| = \hat{Q}(t) $. It seems that the conventional definition gets reversed here!  Interestingly, the complex conjugate of the operator $\hat{Q}(t)$ i,e. $\hat{Q}^*(t)$ follows the correct "Heisenberg prescription" of time translation.  Can someone help me to understand what is going on?


As you may know, Facebook allows users to choose a "vanity URL," allowing easy linking to one's profile. However, once set, this URL cannot be changed and this was done for security reasons, understandably.  I have a friend whose now ex-partner set the URL to be "herfirstname.hislastname" without her permission. She tried to change it after this, but to no avail.  Has anyone successfully contacted Facebook and got them to either disable the name and revert back to an ID or change the name to another?


How to write special character (~) in a URL in a bibliography

I am writing a URL in a web reference in latex. The link contains this special character ~ that when I compile the tex file to PDF, it disappear. The link becomes invalid.  How can I add the special character (~) to my URL in latex reference file (.bib)?  EDIT: The solution of using \url{} will not work with me as this is not a text URL but a bibliography. Here is the script. I use IEEE conference template.  \documentclass[compsoc, conference, letterpaper, 10pt, times]{IEEEtran} \begin{document} \title{Test} \maketitle  This is \cite{citeme}.  \bibliographystyle{IEEEtran} \bibliography{IEEEabrv,ref} \end{document}   The ref file is:  %% %% WinShell 3.3.2.6 %% http://www.winshell.org/ %%  % Strings   % Preamble   % BibTeX Entries @misc{citeme,  author               = {MyName},  title                = {XYZ},  url                  = {https://www.xxx/~vvv},  year                 = {2014},  }   The output as shown below does not include the ~ sign in the URL which make it unreachable link when clicked from the PDF.


Counts of Votes Cast on Profile page not matching under IMPACT and on votes tab?

This may be related to  but that has  so there may be some more code to look at.  In the screenshot below, from , under IMPACT it says that I have 22,071 votes cast but on the votes tab it says that I have 30,383 votes cast.  Is this discrepancy to be expected?


"need not to be neither atomic nor ordered"

Is this double/triple negative grammatically sound?  Ordered operations require that space on disk is allocated sequentially, so spatial ordering corresponds to chronology of operations, but actual disk writes need not to be neither atomic nor ordered.   Explanation:   Words neither and nor emphasize on the fact that both conditions are (independently) allowed to remain unsatisfied, that both are optional. To be more formal, "need not be atomic and need not be ordered". But then again, it becomes a concoction of two negations joined by a conjunction.


Cramer-Rao Casella Berger 7.38 for exponential family

The question states  ''let $X_{1}, \dots, X_{n}$ be random sample from $f(x \mid \theta) = \theta\cdot x^{\theta-1}$ for $0 < x< 1 ; \theta > 0$. Is there a function of $\theta, g(\theta)$ for which there exists an unbiased estimator of $\theta$ whose variance $\textbf{attains}$ the Cramèr-Rao lower bound ? if so find it!". so we have an exponential family, and we can interchange differentiation and integration, so the fisher information term, denominator of the Cramér-Rao lower bound, I calculated as $E \left(\dfrac{\partial}{\partial \theta}[\ln(\theta \cdot x^{\theta-1})] \right)^{2} = -n E \left(\dfrac{\partial^{2}}{\partial \theta^{2}}(\ln(\theta x^{\theta-1}\right) \implies \dfrac{\theta^{2}}{n}$ taking $\dfrac{1}{I(\theta)}$ Now just taking a stab the statistic I've used is $W(X)= \overline{X}$ which I calculate to be UBE since $E[X] = \dfrac{\theta}{\theta + 1}$ and thus E$[\overline{X}] = \frac{\theta}{\theta + 1}$ from my calculations (hopefully right). similarly, if I calculate the variance I get $\dfrac{\theta}{(\theta + 1)^{2}(\theta + 2)} \geq \dfrac{\theta^{2}}{n}$ satisfies the lower bound. If I examine the MLE I find: $\dfrac{n}{\theta} + \sum_{i}\ln(x_{i}) = 0 \implies \hat{\theta_{MLE}} = \dfrac{-n}{\sum \ln(x_{i})}$. the attainment theory states \begin{equation} \begin{split} \frac{n}{\theta} + \sum_{i}\ln(x_{i}) &= a(\theta)[W(\vec{x})-\tau(\theta)]\\  &= n [\frac{ \sum \ln(x_{i})}{n} - \dfrac{-1}{\theta}] \end{split} \end{equation} where if W(x) satisfies the above, then it is the best estimate for $\tau$. We need to use Rao-Blackwell theorem for W in the above equation to show that $\dfrac{1}{\hat{\theta_{MLE}}}$ is the best. Consider Y = \log(X) now applying the transformation with the Jacobian we have \begin{equation} \begin{split} f_{X}(e^{y}) = \theta e^{y(\theta-1)}\cdot e^{y} = \theta e^{y\theta} = f_{Y}(y) \end{split} \end{equation} where E[Y] = $\frac{1}{\theta}$ (Which I think is an unbiased estimator ?) Using the Rao-Blackwell theorem, let $\theta^{\star} = E[Y_{i} \mid \sum y_{i} = t]$ where since $f_{Y}(y)$ is an exponential family then $\sum y_{i}$ can be shown to be sufficient statistic. then \begin{equation} \begin{split}  E[\theta^{\star}] &= E \left[ E[Y_{i} \mid \sum y_{i} = t] \right] \\  &= E\left[ \theta^{\star} \right] \\  &= \frac{1}{\theta^{\star}} \end{split} \end{equation} which really fits into the attainment equation written above! so my guess is to let $W(\vec{x}) = \dfrac{1}{\theta_{\text{MLE}}^{\star}}$ be the best UBE (?)


We need to provide a visual counting proof for the identity above.  At first, we count the number of pairs of $n$ tilings where at least one ends in a square. Then, conditioning on whether the first tiling ends in a square, we need prove the rest.  If we consider the R.H.S of the identity, we see that it is a strip with a length of $(2n-2)$ that we're tiling. How do we approach the problem then? How should one visualize the diagram, given that we need to find the tiling pairs where at least one ends in a square?   N.B what I'm asking for is a visual proof, not by any other means.


Change keyboard shortcuts for Nautilus on Ubuntu 20.04

I just installed Ubuntu 20.04, and I would like to change the tab switching shortcuts from Ctrl + PageUp/PageDown to the more natural Ctrl + Tab / Ctrl + Shift + Tab. How can I do this?


How to print a double with two decimals in Android?

Maybe this is a silly question, but I cannot guess how to solve it if it's not creating a method. Maybe there's a "natural way" to do it, like in C for example. Here's the problem:  I have a var:  double a;   And I want to show it only with 2 or 3 decimals. When I try to show it:  Text.setText("Value of a: " + String.valueOf(a));   It gives something like:     Value of a: 5.234966145   And i would want just     Value of a: 5.23   Without changing the real value of a so it shows the approximate number but works with the real number.


Can we set permission for Custom Setting object for Different Profile

Actually we don't want to show some details to other profile user. I have researched solution for this problem but didn't find a answers for this question.


Validity of fronting important names in titles

In Arabic, one can put for example "Iraq, What is its destiny?" as a title. Is this structure valid in English? If it is, does it have a name? What about the punctuation? Generalizations and limitations?


How can an animated object kept on the surface of an ocean?

I tried to set the ocean as passive rigid body (collision mesh) and a boat as active rigid body.   The boat falls through the ocean. Which technique is recommended for this?  Ideally the boat would follow a curve and the physic simulation would calculate the orientation and level (z-axis).


Showing $\oint \overline{f(z)}f'(z) \,dz$ is purely imaginary.

In attempting this question of showing $\oint \overline{f(z)}f'(z) \,dz$ is purely imaginary, I first considered $\oint f(z)f'(z) \,dz$ which must be zero since $\frac{1}{2}f(x)^2$ is the anti-derivative, and the integral is over a closed curve. Then I thought maybe I'd be able to write $\overline{f(z)}f'(z)$ in terms of $f$ and $f'$ so I may use $\oint f(z)f'(z) \,dz=0$ but I am not sure how this works. Another approach I had is to write $f(z)=\rho(z)e^{i\theta(z)}$, then write the integral as $$\oint \overline{f(z)}f'(z) \,dz=\oint\rho(z)\rho'(z) \,dz + i\oint \rho(z)^2\ \theta'(z) \, dz =i\oint \rho(z)^2\ \theta'(z) \, dz$$ but I don't know if the last integral is real making the right-side imaginary. Does this logic even make sense?


Trying to reference cells A1, then + 5 columns so F1, then + another 5 columns K1, and so on...... Is there a formula I can use which when i drag automatically references +5 columns each time?


I was trying to grant root access to the only user on my machine so I could edit folders and files on the main drive, however it seems I have crashed my system in trying to do so. I used chmod - u on the directory /usr and the GUI started disappearing. I tried rebooting but I can't even load the GUI. Is there an easy way I can fix this without having to reinstall the OS?


I've been using both colortbl and longtable together, on big documents, for years (the former to color rows, columns, or individual cells), and the latter to allow big table to break over pages. In past, using the two together caused no problems at all. However, with the recent update to 'tools' (where longtable lives), colortbl causes problems that it didn't used to.   Here's an MWE - it compile perfectly, until you uncomment colortbl. If this is a non-fixalbe incompatability, I'll have to revert to an older version of the tools packgel. The hundreds of pages I'd have to recode in various books that rely on both longtable and colortbl being able to play nice is more than daunting...  Any suggestions (beyond reverting to an older version of things...)?   \documentclass[12pt]{article}   % \usepackage{colortbl}   \usepackage{longtable}   \begin{document}   \begin{center}  \begin{longtable}{cp{9.5cm}}  \emph{code} & \emph{interpretation} \\  \\[-0.2cm]  \texttt{111} & Lorem ipsum dolor sit amet, consectetur adipiscing elit.   Quisque faucibus mi varius, aliquam quam et, commodo diam. Mauris congue   aliquam dolor, vel sollicitudin enim consequat id.    \\  \\[-0.2cm]  \texttt{110} & Aliquam hendrerit elit dolor, quis venenatis lorem rutrum   ut. Aenean eget ante luctus lacus accumsan varius. Cras massa odio,   fringilla scelerisque laoreet id, pulvinar nec tortor.  \\  \end{longtable}  \end{center}   \end{document}


How to get distance when acceleration is not constant?

I have a background in calculus but don't really know anything about physics.  Forgive me if this is a really basic question.  The equation for distance of an accelerating object with constant acceleration is:  $$d=ut        +\frac{1}{2}at^2$$  which can also be expressed  $$d=\frac{\mathrm{d}x}{\mathrm{d}t}t+\frac{\mathrm{d^2}x}{\mathrm{d}t^2}\frac{t^2}{2}$$  (where x(t) is the position of the object at time t)  That's fine for a canonball or something like that, but what about a car accelerating from 0 to cruising speed?  The acceleration is obviously not constant, but what about the change in acceleration?  Is it constant?  I suspect not.  And then what about the change in the change of acceleration, etc. etc.?  In other words, how does one know how many additional terms to add in the series?  $$d=\frac{\mathrm{d}x}{\mathrm{d}t}t+\frac{\mathrm{d^2}x}{\mathrm{d}t^2}\frac{t^2}{2}+\frac{\mathrm{d^3}x}{\mathrm{d}t^3}\frac{t^3}{3}+\frac{\mathrm{d^4}x}{\mathrm{d}t^4}\frac{t^4}{4}\cdot etc. \cdot ?$$


I fear that my hard drive may be about to break

Whenever I boot my computer, there's almost always a brief interruption in the otherwise normal boot process. A black background with white text, with something along these lines showing:  /dev/sda2 clean: <number>/<bigger number> blocks  Or, perhaps even scarier:  /dev/sda2 clean: <number>/<bigger number> blocks <number>/<bigger number> <number>/<bigger number>  So on and so forth. My question is this: Is my hard drive about to die?


IOrderComparer unique ordering situation

I am trying to order mixed strings in a unique way and am wondering if anyone else has done this. I have found several articles on using IOrderConparer but can not find a solution for my particular sorting problem.  I have the following:  1017, 650, 650C, 650B, W323, 10, 20, 1000, W1000  I need to order them as follows:  10, 20, 650, 650B, 650C, 1000, 1017, W323, W1000  Any help would be appreciated. Thanks.


Is $\mathbb{Z}[x]$ a principal ideal domain?

Is $ \mathbb{Z}[x] $ a principal ideal domain? Since the standard definition of principal ideal domain is quite difficult to use. Could you give me some equivalent conditions on whether a ring is a principal ideal domain?


Error: The uploaded file exceeds the upload_max_filesize directive in php.ini

I am getting error while upload 5mb video file in wordpress media section. How can I solve this issue?


I am using LaTeX to write my scientific paper. My problem is, the paper is in a foreign language. So when I am making chapters, using  \chapter{...}   I get the default "Chapter 1, ..."  I want to set the entire document into French, so that it reads "Chapitre 1, ...". Same for "Table of contents", "Abstract", etc. I don't have a problem with the actual body of text, just those titles that pop up automatically.   Can anybody tell me the way, or should I re-download the program from some French source?


Differences between "xindy" and "makeindex"

I'd like to know which are the essential differences between makeindex and xindy (or texindy) in this sense:   What things can we do with xindy that we can not do with makeindex? or vice versa. What is the primary use of each one of them? Syntactic differences between their style files. (.ist vs .xdy)


Entering Germany with a Passport that is about to expire in 6 mouths

My (Israeli) passport expires on 15/3/2018, and I need to fly from Israel to Germany on 10/9/2017 for 4 nights. I won't be able to renew my passport before the flight in the normal process, only in an express process which costs considerably more and is a greater hassle.  I have asked the Israeli ministry of interior and they told me that I'll be able to leave the country (and come back) as long as my passport is valid, even on the last day before it expires, but from my knowledge, international travel requires a passport that is valid for 6 months.  Will I be able to enter and leave Germany with a passport that expires in 6 months and a few days?


I want to print all lines with storage more than 75% using df command

I want to see lines only when Avail is more than or equal to 75% for the data shown below. Please help me here. vscoder@vscoder-VirtualBox:~$ df -kh Filesystem      Size  Used Avail Use% Mounted on udev            965M     0  965M   0% /dev tmpfs           199M  1.4M  198M   1% /run /dev/sda5       9.3G  7.3G  1.6G  83% / tmpfs           994M     0  994M   0% /dev/shm tmpfs           5.0M  4.0K  5.0M   1% /run/lock tmpfs           994M     0  994M   0% /sys/fs/cgroup /dev/loop1      219M  219M     0 100% /snap/gnome-3-34-1804/66 /dev/loop0       56M   56M     0 100% /snap/core18/1988 /dev/loop2       65M   65M     0 100% /snap/gtk-common-themes/1514 /dev/loop4       56M   56M     0 100% /snap/core18/2066 /dev/loop3      219M  219M     0 100% /snap/gnome-3-34-1804/72 /dev/loop5       66M   66M     0 100% /snap/gtk-common-themes/1515 /dev/loop6       51M   51M     0 100% /snap/snap-store/542 /dev/loop8       32M   32M     0 100% /snap/snapd/11036 /dev/loop9       33M   33M     0 100% /snap/snapd/12057 /dev/loop7       52M   52M     0 100% /snap/snap-store/518 /dev/sda1       511M  4.0K  511M   1% /boot/efi tmpfs           199M   24K  199M   1% /run/user/1000 /dev/sr0         58M   58M     0 100% /media/vscoder/VBox_GAs_6.1.10 vscoder@vscoder-VirtualBox:~$


Ubuntu will not allow me to install programs or updates

I keep getting error messages when I try to install programs via Software Centre or terminal.   This is the code I get in terminal after a failed install.   Preconfiguring packages ... (Reading database ... 540926 files and directories currently installed.)  Removing linux-image-extra-4.4.0-71-generic (4.4.0-71.92) ... depmod: FATAL: could not load /boot/System.map-4.4.0-71-generic: No such file or directory run-parts: executing /etc/kernel/postinst.d/apt-auto-removal 4.4.0-71-generic /boot/vmlinuz-4.4.0-71-generic run-parts: executing /etc/kernel/postinst.d/initramfs-tools 4.4.0-71-generic /boot/vmlinuz-4.4.0-71-generic update-initramfs: Generating /boot/initrd.img-4.4.0-71-generic depmod: WARNING: could not open /var/tmp/mkinitramfs_GEtzy8/lib/modules/4.4.0-71-generic/modules.order: No such file or directory depmod: WARNING: could not open /var/tmp/mkinitramfs_GEtzy8/lib/modules/4.4.0-71-generic/modules.builtin: No such file or directory  gzip: stdout: No space left on device E: mkinitramfs failure cpio 141 gzip 1 update-initramfs: failed for /boot/initrd.img-4.4.0-71-generic with 1. run-parts: /etc/kernel/postinst.d/initramfs-tools exited with return code 1 dpkg: error processing package linux-image-extra-4.4.0-71-generic (--remove): subprocess installed post-removal script returned error exit status 1 Removing linux-image-extra-4.4.0-72-generic (4.4.0-72.93) ... depmod: FATAL: could not load /boot/System.map-4.4.0-72-generic: No such file or directory run-parts: executing /etc/kernel/postinst.d/apt-auto-removal 4.4.0-72-generic /boot/vmlinuz-4.4.0-72-generic run-parts: executing /etc/kernel/postinst.d/initramfs-tools 4.4.0-72-generic /boot/vmlinuz-4.4.0-72-generic update-initramfs: Generating /boot/initrd.img-4.4.0-72-generic depmod: WARNING: could not open /var/tmp/mkinitramfs_gTkI9t/lib/modules/4.4.0-72-generic/modules.order: No such file or directory depmod: WARNING: could not open /var/tmp/mkinitramfs_gTkI9t/lib/modules/4.4.0-72-generic/modules.builtin: No such file or directory  gzip: stdout: No space left on device E: mkinitramfs failure cpio 141 gzip 1 update-initramfs: failed for /boot/initrd.img-4.4.0-72-generic with 1. run-parts: /etc/kernel/postinst.d/initramfs-tools exited with return code 1 dpkg: error processing package linux-image-extra-4.4.0-72-generic (--remove):  subprocess installed post-removal script returned error exit status 1  Errors were encountered while processing:  linux-image-extra-4.4.0-71-generic  linux-image-extra-4.4.0-72-generic  E: Sub-process /usr/bin/dpkg returned an error code (1)   And when doing df -h i got :   Filesystem                   Size  Used Avail Use% Mounted on  udev                         2.7G     0  2.7G   0% /dev  tmpfs                        544M  8.2M  536M   2% /run  /dev/mapper/ubuntu--vg-root  682G   61G  586G  10% / tmpfs                        2.7G  103M  2.6G   4% /dev/shm tmpfs                        5.0M  4.0K  5.0M   1% /run/lock tmpfs                        2.7G     0  2.7G   0% /sys/fs/cgroup /dev/sda2                    473M  468M     0 100% /boot /dev/sda1                    511M  3.6M  508M   1% /boot/efi tmpfs                        544M   80K  544M   1% /run/user/1000 /dev/sdb                     7.5G  5.5G  2.1G  73% /media/aleksc/UUI


How does a phonon cause two electrons to attract each other and form a cooper pair?

We know that like charges repel each other. But my professor claimed that two electrons can attract each other as well. What he said was that due to screening an electron travelling at some speed won't repel another electron, but that they will, in some cases, attract each other due to weak phonon exchange. What does that mean? What is phonon exchange? Do two electrons really attract each other?


When incident light passes through a hydrogen gas, for example, does it have 50% chance (since it's a 1:1 ratio of protons to electrons) of getting absorbed by the proton? Any chance at all? If no, why not? Does a proton have a "bandgap"? If yes, what happens when a photon is absorbed by a proton?


How can a point-particle have properties?

I have trouble imagining how two point-particles can have different properties.  And how can finite mass, and finite information (ie spin, electric charge etc.) be stored in 0 volume?  Not only that, but it can also detect all fields without having any structure. Maybe it can check curvature of spacetime to account for gravity, but how can a point contain the information of what the other fields-vectors are? This seems to mean that also the information/volume in space is infinite.  Mathematically, a point cant have any intrinsic structure, so how does physics which is a mathematical theory explain this?


This was an exam question last year, and I was trying to figure out how to get the answer:  A small company is assigned the class C network 205.67.35.0. You need to divide this network to provide subnets for three departments using fixed-length subnetting. The departments are approximately the same size. Show the network and broadcast addresses for each subnet. Show the slash notation. How many hosts are on each subnet? Are the resulting subnets class C networks?  How would you go about doing this? How would you start it?


In a Game of Thrones episode, when Brienne is taking Jaime back to King's Landing, Jaime quotes that there are "only three people in Westros who can defeat him in a fair duel".However he never mentions their name.Who are these people.Are they named in the books?(I have not read the books yet I am still watching the show.)


To whomever makes the per-site icons: Thank you

I've always been a fan of the unique icons made for . Is there a Stack Exchange employee who makes them? Or are they made by community members on each site?  Whoever made them, I want them to know that they did a fantastic job. I hope they know how much the Stack Exchange community appreciates the work that went into them.


I'm having trouble figuring out a fairly simple QUERY statement in Google Spreadsheets. I'm trying to use a cell reference instead of static values and I'm running into trouble. I keep getting Error: Formula parse error. with:    =QUERY(Responses!B1:I, "Select B where G contains"& $B1 &)   I'm sure it is a simple error, but can someone please show me how to write the above so the QUERY is pulling data from B where G contains the value in cell B1 (cell reference)?


Simple question, How is the unit elements of a polynomial rings? In particular, what is the unit element of the ring $\Bbb Z_4 [x]$?


Build failed issue on Android project in Android Studio

when I build my app it shows this error message:  Caused by: com.sun.tools.javac.util.ClientCodeException: java.lang.NullPointerException


Publication issue of a journal article in Elsevier

Recently, an article of mine got accepted in an Elsevier Journal. Since it was my first publication, I was not very much aware of the whole publication procedure. After acceptance of the paper, I got a link sent for gallery proof. At this stage, I found many grammatical mistakes in the paper, which I should have corrected during the revision stage. I have to agree that I was late regarding this matter. Yet, I incorporated all the extensive corrections and sent back the proof. The journal manager was helpful. He sent me a pdf file with all the corrections incorporated and asked me to approve the revised proof, which I did. Recently, I contacted Elsevier's customer support, whereby I got to know that the paper is in type-setting. It made me a bit confused because the pdf file I got from the journal manager was already corrected and type-setted.   So my question is how could be the paper in the typesetting stage if I have got a prepared pdf file of the revised proof for approval from the journal manager!! If anyone of you is familiar with this scenario, I would appreciate your feedback.


What preposition should I use in this phrase?     In spite of the popularity of modern international music, the traditional music still the more significant and precious thing to/for me.    Should I say "to me" or "for me"?


If my sub-question's answer is more important to me, which answer should I accept?

This is my .  I feel my sub-question's answer is best fit for me. But this question did not include my title.  I am not sure if I should accept this answer because both answer are suitable for acceptance. If I accept my title-related answer, I guess my sub question's answer is more important then my original question's answer.  How can I do it?


Improper Integral from Gradshteyn and Ryzhik

This is the integral one can find in the Introduction of 'Special Integrals of Gradshteyn and Ryzhik the Proofs - Volume I' by Victor H. Moll:  $$\int_0^{+\infty} \frac{dx}{(1+x^2)^{3/2} \left[ \phi(x) + \sqrt{\phi(x)} \right]^{1/2}}, \quad \phi(x) = 1 + \frac{4x^2}{3(1+x^2)^2} \;.$$ The author doesn't know the final answer. It is claimed that it is $\pi / 2 \sqrt{6}$, though numerical integration contradicts this.  Any ideas how to solve it or where to find clues?


duapp.com trying to hijack SO's seach rankings

I know this has happened a lot in the past but I was just snookered into clicking a link for duapp.com after searching google.  stackoverflow.duapp.com/questions/23268645/how-to-read-xml-with-ruby  Like 'real' SO search results, "stackoverflow" comes first in the line so it was easy to make that mistake (I expect intentionally so).  To add to confusion duapp.com after a series of redirects you're directed to page where you can share a 404 error page on social media. duapp.com is hosted by Baidu, but I won't get on my soapbox about that.  Is there anything we can do to remove these useless results from Google search? Is there somewhere else I should report this?


when i want to setText for my textField it throws null pointer exception

when i want to setText for TextField (miniFilePath) it throws null exception i don't know what is wrong with my code?  public class SettingsController {  @FXML private TextField miniFilePath;  @FXML private Button settingExitBtn;  public static String miniFilterPath = new String() ; public static String reportDirectoryPath = new String(); Stage settings = new Stage();    public void display( ){      try {         FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource("Settings.fxml"));          Parent root = (Parent) fxmlLoader.load();         //settings = new Stage();         Stage settings = new Stage();         settings.setScene(new Scene(root));         settings.initModality(Modality.APPLICATION_MODAL);         settings.setResizable(false);         settings.setTitle("settings");          if (!miniFilterPath.isEmpty())             miniFilePath.setText(miniFilterPath);          settings.show();      } catch(Exception e) {         e.printStackTrace();     }  }   this class works as my second window, when i click on one button in another window one instance of this class is called and the window is made. i want that after user set text for a textfield every time user try to open this window the text field is set to the string that is set before.


I've successfully installed Pycharm on my computer. However, I'm not able to install the icon in my desktop.       After executing this command, the window opened correctly.  Question : How could I import the icon in my Desktop?


If extra dimensions are out there, why don't/can't we see them?

String theory proposes the existence of extra space dimensions. Very brilliant minds believe in their existence.   Of course, I could appreciate that they are consequences of mathematical consistencies of String theory. Also, Einstein's theory of gravity is consistent with any number of space dimensions, and there is no sane reason why should the universe must be $3+1$ dimensional or cannot have more than $3$ space dimensions. So extra dimensions could really exist. I don't deny that; don't get me wrong.   But I cannot get my head around that if extra space dimensions are really out there, why can't we see them? I never did understand this. The answer often offered is that since these extra dimensions are small we cannot see them. I can understand microscopic objects in $3$ dimensions cannot be seen but I cannot understand how could dimensions themselves cannot be seen.


I have a cube and I want to cut along an edge so that I can move a face away from the cube.   Basically I want to make a cut along the orange selected closed line and at same time keeping all the faces (I just want to be able to move away faces without deforming the cube).  Note that my initial mesh is just a cube subdivided once, but seems the functions are a bit bugged:  Here's :    Attemp 1   Vertex Edit mode -> Edge Select -> Select ring to cut and press V   Don't work here's the result:     Attemp 2   Vertex Edit mode -> Vertex Select -> Select vertices to make a ring and press Y   Don't work either here's the result:


Can you access the photos you take with the camera?

I was just wondering if you could view the photos you take with the camera?


How do I save php file in var/www/html when it shows error "Permission denied"?

I cannot save a php file in var/www/html and my computer shows error "Permission denied".   How to change permission to save file here?


How to get a single operator from the stmaryrd package?

I am preparing a math document, and would like to use the \bigtriangleup math operator from the package stmaryrd. However, calling the entire package is not an option as it overwrites several commands from mathabx which I am also using. Is there a way I can extract this operator (possibly using a different name, so that mathabx's \bigtriangleup binary operator isn't affected) without having to use the package?


How to reduce Hardware reserved memory on ASUS motherboards?

I have read lots of topics but i still couldn't lower the hardware reserved memory which is over 1GB  There is only 2.21 GB RAM that is being usable by the OS. I had another computer where the usable RAM was 3.5GB. Though, that was Gigabyte motherboard which has no built-in graphic.  The OS is Windows 7 Ultimate 32Bit  Most of the hardware reserved memory i saw is being reserved for the PCI Express with most of its addresses are being reserved for the AMD Radeon.    You can see that there is the reserved addresses from 90000000 to DFFFFFFF on PCI bus.  I have updated the BIOS but that didn't help. I also tried the Msconfig boot settings to uncheck the maximum memory but it did nothing.  Motherboard is ASUS TUF Z270 MARK 2  Are there any BIOS settings that i can disable to save more RAM?


I read this short story a few years ago but I cannot remember the title or author. It was about a human scientist on another planet who was studying the native flora and fauna, trying to find something edible for humans. Does anyone know the title of this story?


Field has incomplete type in forward declaration

I reproduce an error with the following simple file.   It says:      field has incomplete type 'Foo'  bar.h:      class Foo;  class Bar{     private:         int x_;         Foo foo_; // error: incomplete type      public:         void setx(int x) {x_ = x;};         void increment(int);  };   class Foo{  public:     void run(int y,Bar& bar) {bar.setx(y);}; };  void Bar::increment(int i){foo_.run(i,*this);}   Member foo_ must not be a reference or a pointer. The reason for this is that in my actual code,  I cannot initialize Foo in the initialization list of Bar.


I have a directory called "foo bar baz blob". How can I  $ cd "foo bar baz blob"   I have tried with quoting (" and ') and with escaping the blanks (\ ). It does not work. Tab-completion does not work either.  I also have to issue commands with filename arguments that contain spaces. How do I do that? Even MidnightCommander (mc) fails in doing this.  EDIT  Over one year later, I finally found the source of my problem. I have overloaded the builtin cd with a function that automatically lists the files of the changed directory:   $ type cd cd ist eine Funktion. cd ()  {      if builtin cd $1; then         ls;     fi }  $ cd Interner\ Speicher/ bash: cd: Interner: Datei oder Verzeichnis nicht gefunden  $ builtin cd Interner\ Speicher/  $ pwd /run/user/1000/gvfs/mtp:host=%5Busb%3A002%2C018%5D/Interner Speicher  $ ls Alarms   DCIM      Movies  Notifications  Podcasts   SmsContactsBackup Android  Download  Music   Pictures   Ringtones   The solution is easy: I just have to put double quotes around the $1:  if builtin cd "$1"; then   Ooof. Thank you.


What does "relocation offered" mean exactly on Careers?

What does "relocation offered" exactly mean? Is it about sponsoring visa/work permit? I have seen many positions indicating "relocation offered" but then mentioning that applicants must be [I guess already] eligible to live and work in that country.  I think it would be really helpful to be able to filter results based on sponsoring visa, like HN "Who is hiring?" posts. [It has also been .]


How can I draw a dot under a symbol in math mode?

I'm trying to find the equivalent to \d (or \textsubdot) for the math mode.


PCIe Bus Error: Severity=corrected type=Physical Layer ID=00e5(Receiver ID)- How to fix this error on Linux Mint?

Recently, I had installed Ubuntu 19.04 alongside Windows 10. For a couple of days, it was loading fine and then the PCIe Bus error as mentioned in the title started showing up and it was sending infinite messages. I tried several fixes but none of them worked out. Then I tried installed Ubuntu 18.04.2 LTS but started facing the same error after a couple of days. I then installed Linux Mint alongside Windows 10, but the same error comes up.  Hardware Details:  Asus X541U Ram:4+4GB Hard disk: 500 GB(250 for windows 10 & 215 GB for Ubuntu) 64-bit Architecture OS used: Windows 10 Single Language and Linux Ubuntu 19.04, 18.4.2 LTS and  Mint 19.2 Cinnamon   I have added the screenshot of the error. I am facing this error only on this system. On my other system, dual booting is working very well. Why is this happening?


'Microsoft.ACE.OLEDB.12.0' provider is not registered on the local machine not working for Excel, but works for Access

I have used OledbConnection in two places in my solutions, one that reads Access and another that reads Excel. The one that reads Access is fine, but the one that reads excel is giving me error - The 'Microsoft.ACE.OLEDB.12.0' provider is not registered on the local machine.  This is my method where I read Excel and return Datatable.  string CONSTRSTRING = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=<FILENAME>;Extended Properties=\"Excel 12.0;HDR=Yes;IMEX=1\";"; using (OleDbConnection objConnection = new OleDbConnection(CONSTRSTRING.Replace("<FILENAME>", fullFileName))) {     DataSet dsImport = new DataSet();     try     {         objConnection.Open();         DataTable dtSchema = objConnection.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);         if ((null == dtSchema) || (dtSchema.Rows.Count <= 0))         {             throw new Exception("Excel doesn't contain any readable table/tab");         }         new OleDbDataAdapter("SELECT * FROM [" + sheetName + "]", objConnection).Fill(dsImport);     }     catch (Exception ex)     {         throw ex;     }     finally     {         objConnection.Close();     }     return dsImport.Tables[0]; }   Other thing is that if I run the code from VS Debug, it works, but it doesn't when run from the IIS. This only happens for this code, other one for connection access works fine.  ps reading access:  try {     string sAccessConnection = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + filename + ";Persist Security Info=False;";     using (System.Data.OleDb.OleDbConnection con = new System.Data.OleDb.OleDbConnection(sAccessConnection))     {         con.Open();         //doing stuffs         con.Close();     }  } catch (Exception ex) {     throw ex; }   EDIT No, It doesn't have answer there. There it says how to register Microsoft.ACE.OLEDB.12.0. My solution has it working for Access(which means, it is registered) but doesn't work for Excel file. The question is why it is different for Excel and Acces?  And also, if I install x64 Access Driver I get following excetion  Retrieving the COM class factory for component with CLSID {73A4C9C1-D68D-11D0-98BF-00A0C90DC8D9} failed due to the following error: 80070005 Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED)).


continuous mapping is determined by its values on a dense subset of its domain

Question: If f and g are continuous mappings of a metric space X into a metric space Y, let E be a dense subset of X. if g(p) = f(p) for all p $\in$ E, prove that g(p)= f(p) for all p$\in$ X.  Answer: Now, suppose f(p) = g(p) for all p ∈ E. Let x ∈ X\E. Since E is dense in X we have a sequence q$_n$ ∈ E such that q$_n$ → x. So, f(x) = f(lim q$_n$) = lim f(q$_n$) = lim g(q$_n$) = g(lim q$_n$) = g(x). Thus, f(x) = g(x) for all x ∈ X  Hi, I founded the above answer and I'm not sure if the bold line is true and how so if it is. Could you help me understand the equalities in the bold line?  Thank you!


Can't switch to edit mode for some objects, but can for others

(like others asking similarly to myself) I'm just getting started with Blender. I'm following  and thought to give myself something more interesting than creating a single donut, why not three donuts? I'm trying to switch to edit mode for my frosting on my donuts to pull down and create the drizzle, but I can only go into edit mode for a single frosting object. Frosting.002 (selected in the scene collection) is allowing me to enter edit mode:  But I cannot enter edit mode for the other two, even though I have them selected in the scene collection (as pictured below)   I'm not sure what I'm not doing correctly, as it seems this is usually remedied by selecting the appropriate object first (which I thought I did) or restarting Blender. Neither have worked for me, unfortunately. This leads me to believe I've set my objects into a state that needs to be un-done, but I'm not sure what that would be or how to go about fixing it.


"Multi-Collider Thingy" doesn't dropdown on question pages (IE8)

sigh... I am embarrased to admit that my workplace still has us running on Windows XP with IE8 (and that installing Firefox, Chrome or other non-standard software has the extreme potential of getting you fired), so I'm assuming this "bug" is related to my jalopy of a browser and might not even be worth investigating.  I noticed today that the StackExchange™ MultiCollider SuperDropdown™ will not appear if clicked when viewing a question page. It works just fine on the main page and from my profile (and, if memory serves, worked fine yesterday), but when I visit a question and click on it nothing (that I can see) happens.  (This might be related: )


Okay, so I have dynamically generated images via PHP, so not necessarily the same images result. And I've spent the last four hours scanning the internet and trying countless things with jQuery and/or CSS, and I've come up with the following that works.                                        Market.png has a transparent background.  Now, the above works. On mouseover, it displays Market.png with the transparent background part being tile_4.jpg and out mouseout it is tile_4.jpg.  What I want to know: is there ANY way to accomplish the exact same thing as the above with jQuery or CSS? I haven't figured it out, and I've spent hours trying, but I'd rather do something else if at all possible since the above (with massive repetition, the above format is repeated currently around 100 times, but I have plans to expand it to over a 1000 times) will become a bandwidth hog.


Get input from editor (vim/nano/emacs/textmate?)

I was just curious if there's a way to get input not from StdIn but from $EDITOR - be it vim, nano, emacs or even a non-command-line-editor (MacVim/TextMate). What are the options/workarounds/bestpractices?  Basically I'd wish for a workflow as with heredoc - but from the $editor instead.   $ sort -nr << FOO | uniq -c  pipe heredoc> foo  pipe heredoc> bar pipe heredoc> baz pipe heredoc> foo pipe heredoc> FOO    2 foo    1 baz    1 bar


How would you go about proving the following relation about the |sin(x)| value of consecutive numbers?

I've been trying to write a formal proof of the following, but it's been rather annoying. any help is appreciated Prove that for every 3 consecutive numbers n,n+1,n+2. there exists a x = {n,n+1,n+2} number, such that |sin(x)| >= 1/2


Does the Book of Exalted Deeds allow level 10 spell slots?

The artifact Book of Exalted Deeds, DMG p. 222, has the following attribute:     Enlightened Magic. Once you've read and studied   the book, any spell slot you expend to cast a cleric or   paladin spell counts as a spell slot of one level higher.    Therefore, if a level 17+ cleric were to read this book and subsequently cast a spell that scales with slot level, such as Cure Wounds - would he be able to cast the spell at "10th level"?  Cure Wounds:     [...] When you cast this spell using a spell slot of 2nd level or higher, the healing increases by 1d8 for each slot level above 1st.   9th-level slot: 1d8 + 8*1d8 = 9d8 9th-level slot with the Book of Exalted Deeds: 1d8 + 9d8 = 10d8?    Clarification: stating that there currently is no explicit mention of 10th-level slots or spells is not helpful, I'm fully aware of that - it's the whole point of this question.  Therefore, unless you can provide a reference to an official source that explicitly disallows 10th-level spell slots, please refrain from answering. Note that, while they're generally not considered official, a quote from any designer (not just Crawford), will suffice.


"How good do you think it is?" or "How good do you think is it?"

Which one is correct? Leaning towards first one but I am unsure because a more basic version would be "How good is it?"


I have strings that contain white-space and punctuation characters that I want to decompose into individual characters. However, I want to avoid breaking up certain sub-strings that have a specific meaning such as ... or - or \n\r. For example, the string \n\r\n... .. - -.. should be decomposed into ['\n', '\r\n', '...', '.', '.', ' - ', '-', '.', '.']  I've tried using re.findall() and re.split() but without success. The following produced so far the best results (I included only some of the delimiters here to make the example shorter): delimiters = [     r'\r\n',     r'\n',     r' - ',     r' ',     r'...',      r'\.', ] pattern = re.compile(r'(' + r'|'.join(delimiters) + r')') match = pattern.split('\n\r\n... .. - -..') print([m for m in match if m])  which gives ['\n', '\r\n', '...', ' ', '.. ', '- -', '.', '.']  This is very close but I don't understand why ..  and - - are matched.


Ubuntu upgrade issue i.e., from 19.10 to 20.04

I was trying to upgrade the Ubuntu version from 19.10 to 20.04 but in the due process, I am facing the below-mentioned issue. Kindly share the opinion reg the issue.   Error during update A problem occurred during the update. This is usually some sort of  network problem, please check your network connection and retry.   W:Updating from such a repository can't be done securely, and is  therefore disabled by default., W:See apt-secure(8) manpage for  repository creation and user configuration details., E:The repository  'http://archive.ubuntu.com/ubuntu cosmic Release' no longer has a  Release file.


Interpreting interaction terms in logit regression with categorical variables

I have data from a survey experiment in which respondents were randomly assigned to one of four groups:  > summary(df$Group)        Control     Treatment1     Treatment2     Treatment3              59             63             62             66    While the three treatment groups do vary slightly in the stimulus applied, the main distinction that I care about is between the control and treatment groups. So I defined a dummy variable Control:  > summary(df$Control)      TRUE FALSE         59   191    In the survey, respondents were asked (among other things) to choose which of two things they preferred:   > summary(df$Prefer)       A   B  NA's      152  93   5    Then, after receiving some stimulus as determined by their treatment group (and none if they were in the control group), respondents were asked to choose between the same two things:  > summary(df$Choice)   A    B  149  101    I want to know if the being in one of the three treatment groups had an effect on the choice that respondents made in this last question. My hypothesis is that respondents who received a treatment are more likely to choose A than B.       Given that I am working with categorical data, I have decided to use a logit regression (feel free to chime in if you think that's incorrect). Since respondents were randomly assigned, I am under the impression that I shouldn't necessarily need to control for other variables (e.g. demographics), so I have left those out for this question. My first model was simply the following:  > x0 <- glm(Product ~ Control + Prefer, data=df, family=binomial(link="logit")) > summary(x0)  Call: glm(formula = Choice ~ Control + Prefer, family = binomial(link = "logit"),      data = df)  Deviance Residuals:      Min       1Q   Median       3Q      Max   -1.8366  -0.5850  -0.5850   0.7663   1.9235    Coefficients:                     Estimate Std. Error z value Pr(>|z|)     (Intercept)           1.4819     0.3829   3.871 0.000109 *** ControlFALSE         -0.4068     0.3760  -1.082 0.279224     PreferA              -2.7538     0.3269  -8.424  < 2e-16 *** --- Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1  (Dispersion parameter for binomial family taken to be 1)      Null deviance: 328.95  on 244  degrees of freedom Residual deviance: 239.69  on 242  degrees of freedom   (5 observations deleted due to missingness) AIC: 245.69  Number of Fisher Scoring iterations: 4   I am under the impression that the intercept being statistically significant is not something that holds interpretable meaning. I thought perhaps that I should include an interaction term as follows:  > x1 <- glm(Choice ~ Control + Prefer + Control:Prefer, data=df, family=binomial(link="logit")) > summary(x1)  Call: glm(formula = Product ~ Control + Prefer + Control:Prefer, family = binomial(link = "logit"),      data = df)  Deviance Residuals:      Min       1Q   Median       3Q      Max   -2.5211  -0.6424  -0.5003   0.8519   2.0688    Coefficients:                                  Estimate Std. Error z value Pr(>|z|)     (Intercept)                         3.135      1.021   3.070  0.00214 **  ControlFALSE                       -2.309      1.054  -2.190  0.02853 *   PreferA                            -5.150      1.152  -4.472 7.75e-06 *** ControlFALSE:PreferA                2.850      1.204   2.367  0.01795 *   --- Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1  (Dispersion parameter for binomial family taken to be 1)      Null deviance: 328.95  on 244  degrees of freedom Residual deviance: 231.27  on 241  degrees of freedom   (5 observations deleted due to missingness) AIC: 239.27  Number of Fisher Scoring iterations: 5   Now the respondents status as in a treatment group has the expected effect. Was this a valid set of steps? How can I interpret the interaction term ControlFALSE:PreferA? Are the other coefficients still the log odds?


I want to book tickets from Ahmedabad to Boisar in train Jamnagar-Bandra Intercity. But I am not getting that option to book from irctc.co.in. I know this same train goes to boisar and also know that engine and some coaches are added/removed from surat. Thats not the point. Question is how to book the ticket in one go so to get the same seat.  Need an urgent solution want to book for day after tomorrow.


There are $1000$ doors $D_1,D_2,D_3,\dots,D_{1000}$ and $1000$ persons $P_1,P_2,\dots,P_{1000}$. Initially all the doors were closed. Person $P_1$ goes and opens all the doors. Then person $P_2$ closes doors $D_2,D_4,\dots,D_{1000}$ and leaves the odd-numbered doors open. Next, $P_3$ changes the state of every third door, that is $D_3,D_6,\dots,D_{999}$.(For instance, $P_3$ closes the open door $D_3$ and opens the closed door $D_6$, and so on.) This goes on. Finally, person $P_{1000}$ opens $D_{1000}$ if it were closed or closes if it were opened. At the end, how many doors remain open$?$


How to fix warning failed to connect to lvmetad no such file or directory falling back to internal scanning

My Ubuntu laptop which was working fine until recently. My desktop disappeared and all desktop icons are gone. All I have access to is the terminal. In an attempt to fix the problem, I installed GNOME but it made the computer give the error:  Warning! Failed to connect to lvmetad.  No such file or directory    Falling back to internal scanning.   I can press Ctrl+Alt+F1 to start tty1 but I can't get to a graphical user interface. What did I do wrong and how do I fix it?.


Why do light sources appear as stars sometimes?

See for example this photo:    From my experience, the longer the exposure the stronger can this effect be observed. Is this correct? Are there any other factors that influence the creation of these stars (is there a better word for it, by the way?) And what exactly does technically happen?


let's say I am trying to do something like this:  header.h:  template <typename T> class foo {  private:      // members... public:     foo();     ~foo(); }   source.cpp:  template <typename T> foo::foo() {     // do something...  }  template <typename T> foo::~foo() {     // do something...  }   but I keep getting error:   error LNK2019: unresolved external symbol ...   I am working on Microsoft Visual Studio 2015;


How should you ask a question where multiple correct answers are most likely and preferred?

How should you ask a question where the aim is to collate multiple peoples expertise on one subject matter rather than a pure question answer set up. For example:  What ways have people modelled evapotranspiration using satellite data? I have found x,y,z but want to know if there are any additional methodologies.   I know you can use community wiki when answering a question, but not sure what the format should be where one answer will most likely only ever form part of the overall answer.


I'm trying to identify the sort of dust shown below. Several days after wiping a surface in my older apartment it shows up. It looks like synthetic fiber, yet there is no vent or isolation material that I can see, nor is there a carpet, bedding, or clothes in that room. No pet either. Any idea?  As indicated in the comments I did ask a related question regarding the origin of the dust. The answers didn't solve the problem so I'm now asking about the nature of the dust, which isn't quite the same thing. Some folks may recognize it for what it is without wondering where it came from.  Answer: It's fiberglass, see .


Reading number from file into variable -- How to put a number into my document that increments with every compilation?

I am not that much into TeX/LaTex programming ...   but what I want to do is the following:   How to put a number into my document that increments with every compilation  My ideas so far are:   use a text file as storage of the number read in the number add 1 save the number to the text file put the number into the text   I was able to use something like this :  \documentclass{minimal} \newwrite\tempfile \begin{document} \immediate\openout\tempfile=lists.tex \immediate\write\tempfile{1} \immediate\closeout\tempfile \input{lists} \end{document}   () to write to a file but did not manage to read the number from the file into a variable that than could be iterated by one and saved back to the file. Does anyone has an idea?


problem with my array class error CS0120 C#

I'm still learning to code so if there are some issues, please tell me! This is for a school essay.  I'm writing a code that asks some information about a game: game name, the devs behind it, the publisher, and its cost.  The essay has multiple different tasks, like: make a program that uses get set, arrays, methods, or and so on. I made it all into a program, and I got stuck with the error     CS0120 An object reference is required for the non-static field, method, or property 'Program.gameInfoArray'      The code:  class Program {     //the class array that stores the games     public gameInfo[] gameInfoArray = new gameInfo[10];      static void Main(string[] args)     {           bool done = false;         // this is where i get the issue          for (int i = 0; i >= gameInfoArray.Length || done == false; i++)         {             //asks what the game is called             Console.WriteLine("What is the game called:");             string gameName = Console.ReadLine();              //asks who the devolopers are             Console.WriteLine("Who where the devolopers behind the game:");             string devoloper = Console.ReadLine();              //asks who published the game             Console.WriteLine("Who released the game:");             string publisher = Console.ReadLine();              //ask how much the game costs             Console.WriteLine("How much does the game cost:");             string cost = Console.ReadLine();              //inputs the information in to the class array, this is also where i get the issue              gameInfoArray[i].gameInformationGrabber(gameName, devoloper, publisher, cost);              //asks if the              Console.WriteLine("are there any more games? Y/N");             while(true)             {                 ConsoleKeyInfo yesOrNo = Console.ReadKey();                 if ((yesOrNo.KeyChar == 'Y') || (yesOrNo.KeyChar == 'y'))                 {                     done = true;                     break;                 }                 else if ((yesOrNo.KeyChar == 'N') || (yesOrNo.KeyChar == 'n'))                 {                     break;                 }              }         }      } }   The script:  class gameInfo {     private string gameName;     private string devoloper;     private string publisher;     private string cost;      public void gameInformationGrabber(string game, string dev, string publisher, string cost)     {         theGameName = game;         theDevs = dev;         thePublisher = publisher;         theCost = cost;      }     public string theGameName     {         get { return gameName; }         set { gameName = value; }     }      public string theDevs     {         get { return devoloper; }         set { devoloper = value; }     }      public string thePublisher     {         get { return publisher; }         set { publisher = value; }      }     public string theCost     {         get { return cost; }         set { cost = value; }      }  }   Thanks a ton in advance. Sorry if I messed up big time somewhere in the code.


I accidentally killed a noble, now every guard wants to kill me. Is there any way I can get rid of the bounty?


prove that for a continious function if f(q) = 0 for all q where q is rational then all f(x) = 0 when x is real

it is given that f is Continious. and $\forall q\in\mathbb{Q}$ $f(q)=0$    how do I prove that: for all $x\in\mathbb{R}$ :  $f(x) = 0$


What does Stack Exchange use for the edit feature?

The whole feature is pretty dandy. Letting a user edit your post and you can see the before and after with highlights on the changes. What does Stack Exchange use for this feature? I'm hoping its some sort of open source plugin.


Can Network Analyst consider multiple cost attributes?

I'm trying to do a basic service area network analysis in ArcGIS 10.0.  But I have two cost attributes I want to act as the network impedance-- one apportioned along the edges of each line feature, the other a constant.  To be specific, I'm trying to model transit travel.  I have travel time (in minutes) as the primary cost attribute (which is apportioned along the line), but I also want to be able to factor in a constant wait time which is expended at the facility.  The wait time will vary depending on the transit line's frequency.  Because the wait time varies from line to line, I can't just subtract the wait time from the default break values I put into the analysis settings.  For instance, if I want to find out the extent of travel in 20 min and 30 min, and I had only one transit line (with a wait time of 5 min), I could just specify 15/25 as my break values.  But I have multiple transit lines, so I can't specify break values for every line.  Is there any way around this?


Why does the separation of update and upgrade even exist?

I understand that in apt, the command update, updates the list of available packages, but it does not upgrade software that was already installed from these packages.  I also understand that upgrade upgrades any software that I already installed from a package I updated with update as described above.  What was the reason of the Ubuntu/Debian developers to do this splitting of update and upgrade instead work with one command to do both tasks?  This is more of a question on the architectural philosophy of the Ubuntu developers.


How to prove that every ordered field has a subfield isomorphic to $\mathbb{Q}$ using a certain provided function?

How to solve Exercise 2? How does embedding, I suppose in meaning of embedding defined before in the post linked as order-preserving ring homomorphism, $e:\mathbb{Q}\,{\rightarrow}\,K$, imply that for all ordered fields $K$ there exists a subfield of $K$ isomorphic to $\mathbb{Q}$?


Analyze a circuit with two diodes and two voltage rails

I want to find \$I\$, \$I_{D2}\$ and \$V\$ in this circuit. The diodes are made of Silicium. I'm a beginner and normally I would assume the Diode bias and then apply KVL to see if it is true. However, I've only encountered circuits where the wire forms a loop.    How am I supposed to apply KVL in this case? If voltage is the difference in potential between two points, how can I find the voltage of V if one point is outside of the circuit, therefore, outside of KVL application?


How do I play a specific song on a command block without it playing other songs instead?

I'm trying to select a certain song to play on a command block, but when I type in something like "/playsound music.game.creative @p", it will play a different song everytime I activate the command. Is there a way where I can select one of the songs without it playing a different one?


Can i post my article in arxiv for comments from other mathematicians?

I have recently written a paper on Quantum Polynomial Algebra. But I am not studying anywhere, so I havenot got anyone to comment. Even I have mailed a few math professors but they may be to busy to answer. That is why I was asking whether can I post my paper in arxiv to know whether the result that I have obtained is good enough to publish or not? Idonot want to send my paper in reputed journals and get rejected after 2 or 3 months.


In practice, what is the distinction between ESTA and visas?

It is  that ESTA is not a visa - both by the US government and the travelers themselves. However in practice, I find it difficult to see the distinction between ESTA and e-visas:   It costs money, while a true visa-free system is, well, free You have to fill out personal details about yourself to receive it Not everyone who's eligible is approved for it Even if you enter overland, you still have to answer the same questions on form I-94W and pay a fee to enter the country The vast majority of VWP passport holders enter the US by air, so they do need the ESTA   What is the exact distinction then (in practice) that separates ESTA from a regular e-visa?


Why is the color of Avada Kedavra green?

The Avada Kedavra curse is recognisable by the flash of green light and the rushing noise emitted from the caster's wand.   -    I thought green was commonly one of the colors used by light side (the good side). Like in Star Wars, where Jedi light sabers are green or blue, but Sith light sabers are mostly red. But in Harry Potter the light emitted after casting the Killing Curse is green and the defensive spell (casted by Harry Potter) is red. Why the colors are switched in Harry Potter?


Sets and the principle of inclusion and exclusion

I found an interesting problem regarding the principle of inclusion and exclusion. Given $1985$ sets, each containing $45$ items, find their total union, if the union of any two is $89$. This is what I did: First, I found out the intersection of any two. Using the principle of inclusion and exclusion, I managed to find out that |$A_{1}$|$\cup$|$A_{2}$|=|$A_{1}$|+|$A_{2}$|-|$A_{1}$|$\cap$|$A_{2}$|. From this, we know that $89=45+45-x$, where $x=1$. The first thing that came to my mind was that this intersection could be the common intersection of all the sets: A solution I found to the entire problem is that there is one element that every set has in common, and 44 elements that each set does not share with no other set. To clarify, one can imagine a flower, whose petals are individual sets, their only common item being the center of the flower. Each and every pair of sets therefore contains the required 89 elements ($44$ elements on one petal $+$ $44$ elements on the other petal $+ 1$ element in the centre), each set also contains $45$ elements. Therefore, the total sum of all the elements, or the union of all the sets, is $1985\times44+1$. But I do not know how to prove this with formulas and expressions. I am also not sure whether this is correct, because of what I found when I tried to solve a similar problem but only with three sets: The rules of this problem are exactly the same as before, only now we have $3$ sets instead of $1985$. I found out two ways to arrange the elements of the sets which satisfy the rules, each of them having a different total union. If we had a three-set Venn diagram, one solution is this: 1 element in the intersection of them all ($A \cap B \cap C$) 44 elements in each individual set but not in any intersection (in $A$,$B$,$C$) The other solution is this: 1 element in each intersection of every pair, but not in the intersection of them all 43 elements in each individual set. Their unions are different, because while in the first solution, the union is $44\times3+1$, while in the second solution, the union is $43\times3+3$. These are different numbers and therefore I am unsure about my solution to the original problem. My question is whether there is an analytical way to solve this problem, or whether I am missing something.


Did Data have enough memory or "hard drive space"?

I remember an episode in Star Trek TNG (probably first season) where Data is describing some of his internal workings. Among them, he lists that he is equipped with "12 quadrillion" bytes for memory storage. If my math is right that is 12 petabytes.  It seems to me that is severely short for the amount of data he collects every single day.  I found this related question:    However, it seems that Data likely did not back up anything that he learned. I do remember him stating a few times that he forgets nothing.  So this is the question: Is 12 PB enough storage for an android like Data (assuming none of it is taken up by OS and programs)?     Consider some of the implications about massive amounts of data on .    Well, I just found  which says it is 800 quadrillion bits! That is quite a bit more (pun intended) but I am certain that the episode I am thinking of said 12.


Is there any advantage in K-Fold over leave-one-subject-out cross validation?

I experienced in a predictive model for a dataset I have from experiments on human subjects, that the error of the prediction in 10-fold cross validation is less than leave-one-subject-out (leave-one-person-out). I think leave-one-person out has advantage over the K-Fold CV since it takes intra-individual variability into account and thus has higher generalization power than K-Fold. However I am not sure if I am missing any advantage of K-Fold over leave-one-subject-out.


If a function $f: \mathbb{R}\to\mathbb{R}$ is continuous and $f(x+y) = f(x) + f(y)$ for all $x,y\in\mathbb{R}$, then what is this function $f(x)$?


It's well known that Severus Snape was, in one way or another, a Death Eater since he was at Hogwarts. He hung out with the likes of Avery and Mulciber who became well known Death Eaters, he joined Voldemort right after he left Hogwarts, and he basically became Voldemort's right hand man until the very end.   However, in his time as a Death Eater did he ever kill anyone? We know that he was a Death Eater for around 3 years before Voldemort fell; Lily and James died at 21 and they were the same age as Snape, so it would have been 3 years since they left Hogwarts. Then after Voldemort came back in book 4, Snape would have been a Death Eater again for around 3 years. That's a total of around 6 years of Death Eaterhood with Voldemort.  So, in either of these periods, did Snape commit murder as part of his job as Death Eater? I'm not counting a certain death at the end of book 6 for reasons which are obvious if you've read book 7.   Clearly it's much more likely he killed before Voldemort fell since that roughly correlated with the period when he pledged allegiance only to Voldemort, before he became a teacher at Hogwarts. But did he ever do it?


Windows 10 version 1803 (April 2018 Update) makes impossible to remove language

After updating latest release I got stuck with English(US) and English(UK) and non of them can be removed. The Remove button is greyed out. Language packs cannot be uninstalled. Changing default input and display language doesn't solve the problem.


Example of a function $f$ on $X$ to $\mathbb{R}$ which is not $X$-measurable but $|f|$, and $f^2$ are measurable.

Question  The following is from Bartle:  Give an example of a function $f$ on $X$ to $\mathbb{R}$  which is not $X-$measurable but is such that $|f|,$ and $f^2$ are measurable.  Relavant Information  A family $\textbf{X}$ of subsets of $X$ is a $\sigma$ algebra in case:   $\phi, \mathbb{R} \in \textbf{X}$ $X \setminus A \in \textbf{X}$ if $A \in \textbf{X}$ If $(A_n) \in \textbf{X}$, then the union $\bigcup_{n=1}^{\infty} A_n \in \textbf{X}$  Any set in $\textbf{X}$ is called $X-$ measurable.   A function is $X-$ measurable if for every real $\alpha$, the set $\{x \in X : f(x)>\alpha\}$ belongs to $\textbf{X}$  Attempt  Consider the following function: $$f=\begin{cases} 1 &\mbox{ if} \ x \not\in\mathbb{Q} \\                   -1 &\mbox{ if} \ x \in \mathbb{Q}  \end{cases}$$ defined from $\mathbb{R}$ to $\mathbb{R}$ with $\textbf{X}$ being the Borel algebra (the $\sigma$ algebra generated by all open intervals $(a,b)$) Then if $\alpha \in [-1,1)$, the set $\{x: f(x)>\alpha\}$ consists of the irrational numbers. If I can show that the irrationals are not in the Borel Algebra, then I would be done since $|f|=f^2$ is a constant and easily shown to be measurable. Unfortunately I do not know how to show that the irrationals are not in the Borel Algebra.  Edit it has been brought to my attention that the irrationals are in the Borel algebra. I think this is because the rationals, being countable, can be shown to be in the Borel algebra by constructing appropriate small neighborhoods around each rational and then taking the intersections. I now seek to construct a set that is not in the Borel algebra  Alternatively I have tried to define a set other than the irrationals that is not in the Borel Algebra and define a similar function but to no avail. I am currently self studying this book so it would be of great help to me if the answer could contain heuristics on how to tell when a set if borel measurable (although I do not require this in the answer).


All names below are created and do not refer to any specific users or SE sites. In the early days, when user W participated in SE site X, user W gained lots of "reputation" by plagiarising others' answers to answer similar questions; most were copied verbatim. W later got caught by various users and moderators. W was such much into reputation they later formed a group of friends to vote for each other. W then got caught and suspended for one year. W came back. W learned the lesson that voting groups are likely to be detected. W then created careful sockpuppets to upvote 1 or 2 of their posts every few days. Several years later, W was finally caught again and suspended for another one year due to voting irregularities. W then came back. And again, W is becoming more careful. Yet, a few months later, this user got suspended again for a few days because of voting irregularities. How many voting irregularities do we tolerate? Would the community managers consider giving such users a permanent suspension?


A sequence of partitions that splits up every triple

The question We are given a set of size $m$, which we can assume to be the set $[m] = \{1,2,\dots,m\}$. Say that a sequence $(A_i,B_i,C_i)_{i=1}^k$ triple-splits the set $[m]$ if:  For each $i$, $(A_i, B_i, C_i)$ is a partition of $[m]$: $A_i,B_i,C_i$ are pairwise disjoint subsets of $[m]$, and $A_i \cup B_i \cup C_i = [m]$. For every $3$-element subset $\{x,y,z\} \subset [m]$, there is an $i$ such that $A_i \times B_i \times C_i$ contains a permutation of $\{x,y,z\}$. Iin other words, there is an $i$ such that the three elements $x,y,z$ are in different parts of the partition $(A_i, B_i,C_i)$.  What is the smallest $k$, in terms of $m$, for which we can find such a sequence? I am fine with asymptotic answers, and I am interested in both upper bounds (ideally constructive ones) and lower bounds better than $\Omega(\log m)$. This can be stated in terms of hypergraphs. What is the smallest $k$ for which we can cover the complete $3$-uniform hypergraph on $m$ vertices with $k$ tripartite $3$-uniform hypergraphs? Motivation This is based on my solution to  on Puzzling.SE. A sequence that triple-splits $[m]$ would give us a solution to the problem of finding the third-smallest element of $\{x_1,x_2,\dots,x_m\}$. Specifically, the formula would be $$    \min\Big\{\max\{\min\{x_i : i \in A_1\}, \min\{x_i : i \in B_1\}, \min\{x_i : i \in C_1\}\}, \\        \qquad\max\{\min\{x_i : i \in A_2\}, \min\{x_i : i \in B_1\},  \min\{x_i : i \in C_2\}\}, \\        \dots \\        \qquad\max\{\min\{x_i : i \in A_k\}, \min\{x_i : i \in B_k\}, \min\{x_i : i \in C_k\}\}\Big\}. $$ Each max is a max of three distinct elements from $\{x_1, \dots, x_m\}$, so each max is at least the third-smallest element. On the other hand, if the sequence triple-splits $[m]$, and $x_a,x_b,x_c$ are the three smallest elements, then there has to be some $i$ for which $A_i, B_i, C_i$ each contain one of $a,b,c$. For that $i$, the max we'll get will be $\max\{x_a,x_b,x_c\}$: exactly the third-smallest element.


Evaluate the limit $\lim\limits_{n \to \infty} \frac{1}{1+n^2} +\frac{2}{2+n^2}+ \ldots +\frac{n}{n+n^2}$

Evaluate the limit   $$\lim_{n \to \infty} \dfrac{1}{1+n^2} +\dfrac{2}{2+n^2}+ \ldots+\dfrac{n}{n+n^2}$$   My approach :   If I divide numerator and denominator by $n^2$ I get :   $$\lim_{ n \to \infty} \dfrac{\frac{1}{n^2}}{\frac{1}{n^2} +1} +\dfrac{\frac{2}{n^2}}{\frac{2}{n^2} +1} + \ldots+ \dfrac{\frac{1}{n}}{\frac{1}{n} + 1}=0$$   but the answer is $\dfrac{1}{2}$ please suggest how to solve this.. thanks.


why is my if statement executing when the conditions are not true?

String parkingStringChoice; System.out.println("Would you like to purchase parking? (Y or N)"); parkingStringChoice = scnr.nextLine(); int parkingChoice;  switch(parkingStringChoice) {     case "Y":         System.out.println("You have parking");         parkingChoice = 1;         break;     case "N":         System.out.println("You dont have parking");         parkingChoice = 0;         break;  }  if (parkingStringChoice != "Y" && parkingStringChoice != "N") {     System.out.println("Reenter valid input.");     System.exit(0); }   The above portion is my code for a portion of my program asking if the user wants parking or not.  I am trying to write an if statement to make sure if the user does not input Y or N it will print an error and then exit.  Instead of this, it is currently executing the if statement at all times, whether Y, N, or some other string is entered.  Any help is appreciated, thanks.


Gay and straight are to sexual orientation as transgender and cisgender are to ______?

Gay and straight are to sexual orientation as transgender and cisgender are to ______  What word would fit best in the blank here? Some options that don’t quite seem to fit:  Gender orientation: Doesn't seem to have widespread adoption or a well-defined meaning. Gender identity: It would seem more appropriate to say something like “my gender identity is female” rather than “my gender identity is cisgender”. The categories don’t align. Gender expression: This refers only to the outwardly visible aspects of gender, not to how a person actually identifies.


Am using Lyx to write report. I have to add some figures. But when compiling my file all the figuers are displayed on the top of the page. Any help is appreciated.


Calculating $\lim_{x\to0} \left\lfloor\frac{x^2}{\sin x \tan x}\right\rfloor$

Find $$\lim_{x\to0}  \left\lfloor\frac{x^2}{\sin x \tan x}\right\rfloor$$ where $\lfloor\cdot\rfloor$ is greatest integer function   I am a high school teacher. One of my students came up to ask this limit.  For $\lfloor\frac{\sin x}{x}\rfloor$, I have used $\sin x > x$ using increasing decreasing functions.  I tried to prove $x^2 > \sin x \tan x$ using increasing /decreasing  function but I am not getting it.


TeX capacity exceeded using pgfplots with/without externalization when compiling with PDFLaTeX

I have very big issues in externalizing and generella produce plot with latex. I'm compiling with PDFLatex and the compiler is texmaker. I'm compiling my thesis that consists in different chapters and some plots. i already red all the topics about this problem but i can't get a solution. the problem are:  first, latex refuse to externalize picture, so i added --enable-write18 in the library with \usetikzlibrary{external}\tikzexternalize. after that, some plot were drawn, but memory exceed problem come along; i add the line --extra-mem-bot=100000000 (now it's removed) but after i reach 21000000000 it can compile no more;  At this moment the lines \usetikzlibrary{external}\tikzexternalize are commented because the compiler totally stopped to work even with them on and only loaded the picture already created, even i modify them. what would i do to solve the problem?


Why $\|x\| \leq \liminf_{n\in\mathbb{N}} \|x_n\|$

If $\|x\|$ converges weakly to $x$, then $\|x\| \leq \liminf_{n\in\mathbb{N}} \|x_n\|$.  Can someone explain this? Thanks.


Prove that $M/N$ and $N$ are finitely generated $\Rightarrow M$ is finitely generated.

Let $M$ be an $R$-module, and $N$ be it's submodule.  I need to prove that if both $M/N$ and $N$ are finitely generated, then so is $M$.  How to prove it? Don't have any ideas at the moment.


QGIS Composer - Inserting OS Grid Reference

I would like to add an OS grid reference to QGIS Composer, i just need to show the figures.  Running on QGIS 2.18.3.


Proof of the equality $\sum\limits_{k=1}^{\infty} \frac{k^2}{2^k} = 6$

Show that for $k$ running over positive integers  $$ \sum_{k=1}^\infty \frac{k^2}{2^k}=6 .$$ We can use finite calculus.