Commutator Subgroup of Direct Product equals the Direct Product of the Commutator Subgroups

I need to prove that $(G_{1}\times G_{2})^{\prime} = G_{1}^{\prime} \times G_{2}^{\prime}$, where $G^{\prime}$ denotes the commutator subgroup of $G$ - i.e., $G^{\prime}=[G,G]$, the subgroup generated by all commutators of elements of $G$.   Recall that the commutator of two elements $x$ and $y$ in a group $G$, denoted $[x,y]$ is defined to equal $x^{-1}y^{-1}xy$.  I have posted my proof as an answer below. Could somebody please take a look at it and let me know if it's okay? If not, please let me know what I need to do in order to fix it. Thank you. :)    Edit: I have been informed that my answer given below actually shows only equality of the set of commutators, and that $G^{\prime}$ consists of products of commutators. So, this question is no longer a proof check, but I am asking specifically how to fix what I have written below in order to make it actually answer the thing I set out to prove. I am having a bit of trouble understanding some of the hints given me thus far, and am going to need more detail in any answers given in order for them to be helpful.


How to recreate Task Recurrence on VF page

Has anyone replicated the task recurrence functionality on a VF page? It looks like it uses javascript in an Activity.js file to do the showing/hiding of applicable fields based on the user selecting the frequency (Daily/Weekly/etc.) My VF override page doesn't seem to include this Activity.js file.  I was curious if anyone had a snippet of code that replicated this or perhaps knew of a VF component. I'm hesitant to try hack it too much to include Activity.js, rely on that, and just hope Salesforce never changes it.  My other alternative is to just replicate it all manually! :)


I have a directory full of media. I would like to search similar videos and hand-remove certain copies (those that are too short, too long, have watermarks, don't have watermarks, &c.).  How can I find videos that are somewhat similar to each other?


How to trim a particular word from a string and store it?

I am storing the URL given below in a field in DE:    From this , i want to trim the utm_campaign value in the field .  Finally it should look like this  4in1tbd_20170421  Is this possible through SQL? Can anyone give me a suitable solution please?


I am wondering how to evaluate the following sum:  $$\sum_{n=0}^{\infty}\frac{1}{(n^4+n^2+1)n!}.$$  In wolfram alpha I find it is equal to $e/2$ .  I have used the residue method but I didn't succeed and also using digamma function is still hard for me, my problem is treating the $n!$.


Proving that $D^{-1}\mathbb{Z}\cong \mathbb{Z}[x]/(px-1)$

Let $p$ be prime, and $D=\{1,p,p^2,p^3,\dots\}$. The ring $D^{-1}\mathbb{Z}$ is defined as the set of fractions $\{\frac{n}{d}:n\in\mathbb{Z},d\in D\}$. How would I show that the ring $D^{-1}\mathbb{Z}\cong \mathbb{Z}[x]/(px-1)$? I know by the first isomorphism theorem that the ideal $(px-1)$ is the kernel of a homomorphism $\varphi :\mathbb{Z}[x]\rightarrow D^{-1}\mathbb{Z}$.   My issue is that I'm not sure how to actually construct this homomorphism. Any thoughts?


A question about a bounded linear surjective operator

This is a question from Rudin's Functional Analysis.  Let $T\in \mathcal B(X,Y)$ and $T(X)=Y$. I have to prove that there exists $\delta>0$ such that $\{S\in \mathcal B(X,Y):S(X)=Y\}\supset B_{\delta}(T)$, where the ball is with respect to the metric generated by the operator norm.  I could not proceed. Any help is appreciated.


Force on rope with accelerating mass on pulley

I have a pretty basic pulley problem where I lack the right start.  A child sits on a seat which is held by a rope going to a cable roll (attached to a tree) and back into the kid's hands.    When it sits still, I believe that the force on either side of the rope must be equal to keep is static, therefore each rope holds $\frac{1}{2}mg$, the cable roll has to carry the full $mg$.  Now, the kid wants go up with $\frac{1}{5}g$. For the whole system to accelerate up, the cable roll has to support another $\frac{1}{5}mg$ resulting in $\frac{6}{5}mg$ of force.  The question that I cannot answer is:     How much force does the kid need to apply onto the rope in its hands?   As I said before, $F_k$ (kid) and $F_s$ (seat) have to be $\frac{6}{5}mg$. So I get this:  $$F_k + F_s = \frac{6}{5}mg $$  In order to solve for either one, I would need another equation. The forces cannot be equal, otherwise there would be no movement of the rope. So I just invented the condition, that the difference of the forces has to be the acceleration:  $$F_k - F_s = \frac{1}{5}mg $$  I can solve this giving me $F_s = \frac{5}{10}mg$ and $F_k = \frac{7}{10}mg$ which will sum up to the total force.  But is this the right approach at all?


Stop enforcing forbidden characters in my input field

In my registration form of my website, I have a field for email. It is like  <input type="email" name="email" size="25" maxlength="200" required pattern="^[A-Za-z0-9@.]+" required />   So, in this field, a person can only write the few characters which are not restricted.  But today someone tried to access my website and fulfilled his registration using some code like  ((selectsleep(25)))a--1   My question is, how can someone fill and submit these type of characters in that input field? Is there any lacking in my code? And second question is, how can I stop this type of characters to be submitted?


Let $f_{k+1}(x)=f_{k}(\cos x)$ and $f_{1}(x)=\cos x$ then $\lim_{k\to\infty}f_{k}(x)=0.73905\cdots$  I was just piddling around with the calculator one day. I don't know what happened but I just happened to take the cosine of a single number (in radians) repeatedly. It converged to a single value $0.739085133\dots$ It converged to this same thing for every number I tried. Like for example, the cosine of the cosine of the cosine of the cosine$\dots$ of any arbitrary value is equal to that.  Please tell me if I have made a new observation, or if it's just a false alarm.


For any $n ≥ 2$, there exists a $n × n$ real matrix $A$ such that the set $\{A^p | p ≥ 1\}$ spans the $\Bbb R$-vector space $M_n(\Bbb R)$.

True or false?      For any $n ≥ 2$, there exists a $n × n$ real matrix $A$ such that the set $\{A^p \mid p ≥ 1\}$ spans the $\Bbb R$-vector space $M_n(\Bbb R)$.   I am not getting any clue on how to approach!! One thing that came in my mind is to deal with polynomials $f(x)=a_0+a_1x+a_2x^2+\cdots+$ which is satisfied by $A$ but this will not put any effect as we have to create an arbitrary matrix in the spanning set.


What should we do about a UK Standard Visitor visa refusal (V4.2(a,c))?

Today, my mother's UK visit application got rejected. We live in Pakistan, and here, mostly, the property is owned by the males. Therefore, in our case, my mom does not have any property in her name. But both my mom and dad share a joint bank account. And my mom is a housewife, therefore, she is supported by my dad.   With her visa application, I submitted dad's ID card copy, her bank statement, and my dad's land document (along with sponsor's documents like bank statement, employer's letter, pay-slips, property inspection letter). But still her application got rejected.  Can someone please tell what should we do about it and what should we submit to overcome this rejection again?


Deriving Heaviside-Feynman formula for the electric field of an arbitrarily moving charge from Lienard-Wiechert potential

I've been trying to derive this (which Feynman warns takes a lot of work) for a couple of days now, without success. My current best derivation which however doesn't give the right answer is:  First, realizing that to go from derivatives with respect to time, $t$, to ones with respect to retarded time, $t'=t - \frac{r}{c}$, we need:  $$\frac{d t'}{d t} = 1 - \frac{\dot{r}}{c} \tag{1}$$  Where $r=|\vec{r}|=|\vec{r}_{1}-\vec{r}_{2}(t')|$ Where $\vec{r}_{1}$ and $\vec{r}_{2}(t')$ are the fixed (time-independent) position vector of the observation point and the retarded position vector of the charge (at time $t'$), respectively. And the dot represents derivation with respect to $t$  The Lienard-Wiechert potentials are:  $$\phi(\vec{r}_{1}, t) = \frac{q}{4\pi\epsilon_{0}(r-\frac{\vec{v}\cdot\vec{r}}{c})}$$ $$\vec{A}(\vec{r}_{1}, t) = \frac{q\vec{v}}{4\pi\epsilon_{0}c^{2}(r-\frac{\vec{v}\cdot\vec{r}}{c})}$$  Where $\vec{v} = \frac{d \vec{r}_2}{d t'}|_{t'=t - \frac{r}{c}}$; that is, the standard retarded velocity.  Now, it is useful to note:  $$\frac{1}{1-\frac{\vec{v}\cdot\vec{r}}{rc}} = \frac{1}{1+\frac{\frac{d r}{ dt'}}{c}} = \frac{1}{1+\frac{\dot{r}}{c-\dot{r}}} = 1-\frac{\dot{r}}{c} \tag{2}$$  Where we have used $(1)$ to transform the time derivative.  Then I rewrite the LW potentials as:  $$\phi(\vec{r}_{1}, t) = \frac{q}{4\pi\epsilon_{0}r}\Big(1 - \frac{\dot{r}}{c}\Big)$$ $$\vec{A}(\vec{r}_{1}, t) = \frac{q\dot{\vec{r}}}{4\pi\epsilon_{0}c^{2}r}$$  Finally, I can work out the electric field:  $$\vec{E} = - \vec{\nabla} \phi - \frac{\partial \vec{A}}{\partial t} = \frac{-q}{4\pi\epsilon_{0}}\bigg(\frac{-\vec{r}}{r^{3}}\Big(1 - \frac{\dot{r}}{c}\Big)-\frac{1}{rc}\vec{\nabla}\dot{r}+\Big(\big(1 - \frac{\dot{r}}{c}\big)\frac{1}{r^{2}}\frac{dr}{dt'}-\frac{1}{r}\frac{d}{dt'}\big(1 - \frac{\dot{r}}{c}\big)\Big)\frac{\vec{\nabla}r}{c}+\frac{\ddot{\vec{r}}}{c^{2}r} - \frac{\dot{\vec{r}}\dot{r}}{c^{2}r^{2}}\bigg)$$  Where the spatial gradient is with respect to $\vec{r}_{1}$, and where I've had to derive with respect to $\vec{r}_{1}$ directly and then with respect to $t'$ because it too depends on $\vec{r}_{1}$ through $r$. Now, $\vec{\nabla}\dot{r} = \frac{\partial}{\partial t}(\vec{\nabla}r)=\frac{\partial}{\partial t}(\frac{\vec{r}}{r})$ because these partial derivatives commute. Finally, I can again convert the time derivatives using $(1)$ so:  $$\vec{E} = \frac{q}{4\pi\epsilon_{0}}\bigg(\frac{\vec{r}}{r^{3}}-\frac{\vec{r}\dot{r}}{r^{3}c}+\frac{1}{rc}\frac{\partial}{\partial t}\Big(\frac{\vec{r}}{r}\Big)+\frac{\ddot{\vec{r}}}{c^{2}r} - \frac{\dot{\vec{r}}\dot{r}}{c^{2}r^{2}} - \frac{\vec{r}}{rc}\Big(\frac{\dot{r}}{r^{2}} + \frac{\ddot{r}}{r(c-\dot{r})}\Big)\bigg) = \frac{q}{4\pi\epsilon_{0}} \bigg(\frac{\vec{r}}{r^{3}} + \frac{r}{c} \frac{\partial}{\partial t}\Big(\frac{\vec{r}}{r^{3}}\Big)+\frac{1}{c^{2}}\Big(\frac{\ddot{\vec{r}}}{r} - \frac{\dot{\vec{r}}\dot{r}}{r^{2}}-\frac{\vec{r}\ddot{rc}}{r^{2}(c-\dot{r})}\Big)\bigg)$$  The first two terms are right but the third, although close, isn't right (specially annoying is that $c-\dot{r}$ in the denominator). The actual equation is found in . I've found a  (pages 22-23) that says that the Heaviside-Feynman formula can't actually be derived from the LW potentials, but I don't know, I think I trust Feynman more. Has anyone here done this derivation?


How to select data from Database which contains special characters like aٌ ,Á, É?

Here is the table :  //Creating The Table. CREATE TABLE `locations` (      `location` VARCHAR(255) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL ,     `id` INT NOT NULL AUTO_INCREMENT ,     PRIMARY KEY (`id`) ) ENGINE = InnoDB;  //Inserting 2 Values To The Table , One Of Them Containing Special Char. INSERT INTO `locations` (`location`, `id`) VALUES ('New York', NULL), ('Alfonso Castaٌeda', NULL);  //Connecting To The DB & Setting utf-8 $pdo = new PDO($dsn , $user , $password , array(PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES utf8"));   In the PHP file which is utf-8 encoding:  <meta charset="UTF-8">  ini_set('default_charset','utf-8'); header ('Content-type: text/html; charset=utf-8');  $charset = $pdo->prepare('SET CHARSET "utf8"'); $charset->execute();  $query = 'Alfonso Castaٌeda'; utf8_encode($query);  $stmt = $pdo->prepare('SELECT * FROM locations where location = :loc").'"'); $stmt->execute(array('loc' => $query)); $values = $stmt->fetchAll();  var_dump($values);   The printed code on running the php file:  array(0) { }   But when I execute this query on PHPmyAdmin on my localhost:  SELECT * FROM locations where location = "Alfonso Castaٌeda"   I get :  +------------------------+       location        id   Alfonso Castaٌeda    2 +------------------------+


In bash, read after a pipe is not setting values

With ksh I'm using read as a convenient way to separate values: $ echo 1 2 3 4 5 | read a b dump $ echo $b $a  2 1 $  But it fails in Bash: $ echo 1 2 3 4 5 | read a b dump $ echo $b $a     $  I didn't find a reason in the man page why it fails, any idea?


I am working to build a reinforcement agent with DQN. The agent would be able to place buy and sell orders for a day trading purpose. I am facing a little problem with that project. The question is "how to tell the agent to maximize the profit and avoid the transaction where the profit is less than 100$".  I want to maximize the profit inside a trading day and avoid to place the pair (limit buy order, limit sell order) if the profit on that transaction is less than 100$. The idea here is to avoid the little noisy movements. Instead, I prefer long beautiful profitable movements. Be aware that I thought using the "Profit & Loss" as the reward.  "I want the minimal profit per transaction to be 100$" ==> It seems this is not something that is enforceable. I can train the agent to maximize profit per transaction, but how that profit is cannot be ensured.  At the beginning, I wanted to tell the agent, if the profit of a transaction is 50 dollars, I will remove 100 dollars, then It becomes a penalty of 50 dollars for the agent. I thought it was a great way to tell the agent to not place a limit buy order if you are not sure it will give us a minimal profit of 100$. It seems that all I would be doing there is simply shifting the value of the reward. The agent only cares about maximizing the sum of rewards and not taking care of individual transactions.   How to tell the agent to maximize the profit and avoid the transaction where the profit is less than 100$? With that strategy, what guarantee that the agent will never make a buy/sell decision that results in less than 100 dollars profit? Does the sum of reward - # transaction * 100 can be a solution?


I have a custom button which I want to show on only one ListView of Lead. Currently it is shown on all the list views. How can it be possible?


on MacOS, how to switch to different windows of the same application EASILY?

I found it very frustrating that CMD+TAB switches only between applications and not between windows of the same application. If I have several windows of Safari open, CMD+TAB will show only ONE instance of Safari. I know that SOME applications support CMD+` or something like this, but not all of them, some applications have also different keys shortcuts. I usually set up my key shortcut in preferences as "Move focus to next windows" and sometimes work, but for example, Terminal doesn't accept it. It's very frustrating, is there a way do move fast between windows? I also thought that swiping to another desktop was cool, but again, one application with all its windows can stay in only one desktop...


Show output only if both words match using grep

If packagehello does not match, the output is still displayed.  Aim: to see no output in situation 2  Situation 1:  user@hostname ~]$ sudo yum list 'package*' packagehello packagehello package2world packagehello package2world   Situation 2:  user@hostname ~]$ sudo yum list 'package*' | grep -E 'package1.*|package2.*' package2world package2world   How to show the output only if both words match using grep?


How to run linear regression with constraints in R?

If I have the following data  n<-1000 x1<-rnorm(n,1,1) x2<-rnorm(n,2,2) x3<-rnorm(n,3,3) e<-rnorm(n) y<-3+0.5*x1+0.2*x2+0.3*x3+e   I want to fit a linear model between $y$ and $x$ like: $$y=\alpha+\beta_1x_1+\beta_2x_2+\beta_3x_3+\epsilon$$ The unconstraint linear regression in R is  fit=lm(y~x1+x2+x3)   Now if I have some extra constraints for the coefficients:  (i) $\beta_i\ge0$, for $i=1,2,3$;  (ii) $\displaystyle\sum_{i=1}^3\beta_i=1$.  I still want to run a linear regression but with the two constraints above. How can I implement this constrained linear regression in R?


How to reference cell to the left (Excel)

I'm trying to do some calculations based on team results in Excel. The format is:  Team | Player | Yards  A   |   x    |  100  B   |   y    |  142  A   |   z    |   93   I'd like to be able to sum all the yards for a particular team, so for example if there are several players from team A then it sums their yardage. How would I go about doing this?   The dataset is long enough that it is impractical to do it all manually.  Thanks in advance!


Solve the equation $ z^2 + \left\vert z \right\vert = 0 $, where $z$ is a complex number.

I've tried solving this, but I'm stuck at one point.  Here's what I did:  Let $ z = x + yi $, where $x, y \in \mathbf R$  Then , $ (x + yi)^2 + \sqrt{x^2 + y^2} = 0 $  Or, $x^2 + {(yi)}^2 + 2xyi + \sqrt{x^2 + y^2} = 0 $  Or, $ x^2 - y^2 + 2xyi + \sqrt{x^2 + y^2} = 0 + 0i$  Thus, $ x^2 - y^2 + \sqrt{x^2 + y^2} = 0\qquad\qquad\qquad\qquad\qquad\qquad\ (i)$ and $2xy = 0 \qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad(ii)$  If $2xy = 0$, then either $x = 0 $ or $y = 0$  Now, if I take $ x = 0$, and subsitute in $(i)$, I get either $y = 0$ or $y  = 1$.  So far, so good, but if I take $y = 0$, and substitute in $(ii)$:  We have $x^2 + \sqrt{x^2} = 0$  so $x^2 = -\sqrt{x^2} $  or $x^2 = -x$  or $\frac{x^2}{x} = -1 $  or $x = -1$  However, this solution doesn't satistfy the equation $x^2 + \sqrt{x^2}$ or the original equation.   What am I doing wrong here ?


How to import text(scripted expression for driver) together when linking a character

I used the phrase bpy.app.driver_namespace to create a function for scripted expansion that can be used in the driver and it works well in the local character file. However, when I try to bring my character through a link in another blend file, the text is missing text. To use the character, you had to manually link text to set the execution and registration options. However, the latest characters in Blender cloud, such as Spring and Rain, automatically come in with text when link. How do I achieve this?


How to use one of the 2 context filters in a view (with an OR)?

I have a view with 2 relations with the store for 2 different entities. I want to filter the view with the store id for the 2 relationships. I created 2 context filters in the views. You must use the first context filter OR the second. How to do this ? If 2 filters are added, there are no results


How many dice does the GM roll when challenging the players?

I'd like to run a game of , but I'm not sure how many dice I roll when the characters face various challenges. I'm under the impression that it's supposed to be the same number of dice the character uses, but that seems to make impossible tasks far too easy to perform. Is there a general rule saying how many dice the GM rolls against a character's attempt at a given task?  Should the GM's dice equal the character's dice, or should the GM's dice vary depending on the task's difficulty?


Delete all lines of text that isn't all numbers

I have a wordlist that I'd like to extract every line of text from that contains only numbers, to a new file.  What do I do?


Limiting downvotes to those with an accompanying comment

Don't you think a downvote without a comment, even a 2 word comment, is just unnatural, non constructive and against Stack Overflow regulations itself?  I mean if someone wants to downvote, sure thing go ahead, yet at least give 1 reason for it so that the asker can know why. And if you don't want to comment, then you don't want to contribute, hence the downvote is meaningless and non constructive!   Why don't you limit "down-votes" to be submitted with a comments only? -inside post comment for a down-vote topic arrow-  edite : question splited into two topics !


Do I need a work visa if I'm freelancing while traveling?

I'm planning to work with a company in the USA while I travel the world (I'm a US citizen). I don't plan to be in any country more than a month, and plan to stay in hotels, hostels, and Airbnb's.  Will I need to obtain a work visa in each country?


Find an equation in spherical coordinates for the surface represented by the rectangular equation

The rectangular equation is $$x^2+y^2-8z^2=0$$ $$x^2+y^2=8z^2$$ Know in the relationship between rectangular and spherical coords. we can manipulate our given to fit the form: $$x^2+y^2+z^2=9z^2$$ $$\rho^2=x^2+y^2+z^2, \space z=\rho\cos(\phi)$$ $$\rho^2=9\rho^2\cos^2(\phi)$$ $$1=9\cos^2(\phi)$$ $$\frac{1}{3}=\cos(\phi)$$ $$\arccos\left(\frac{1}{3}\right)=1.23 \space rads$$ And so the equation in spherical coords. is $\phi=1.23$ I know my math is correct but I have the wrong answer so ilm not sure where I went wrong.


In Skyfall, there is a distinct scene where Silva has revealed the true identities of several MI6 agents via YouTube, yet there is no hint that Bond's identity is anything of a pseudonym, because we in fact see his parents' gravestone at his former residence.   What makes Bond so special?


Using StartCoroutine() and WaitForSeconds()

I am trying to perform two operations. First I want to increase the size of a GameObject and then delay for 0.1s before returning it back to its original size. However, when I try using StartCoroutine(), it keeps giving me the error :  An object reference is required to access not-static members   even though I made my Delay() function static. Can somebody please tell me what I'm doing wrong?  public static void MoveSelected(int choice) {     GameObject rock1 = GameObject.Find("Rock1");     GameObject paper1 = GameObject.Find("Paper1");     GameObject scissors1 = GameObject.Find("Scissors1");      Vector3 scl;      if (choice == 1)     {         scl = rock1.transform.localScale;         scl.x *= 1.1f;         scl.y *= 1.1f;         rock1.transform.localScale = scl;          StartCoroutine(Delay());          scl.x /= 1.1f;         scl.y /= 1.1f;         rock1.transform.localScale = scl;     }     else if (choice == 2)     {         scl = paper1.transform.localScale;         scl.x *= 1.1f;         scl.y *= 1.1f;         paper1.transform.localScale = scl;          StartCoroutine(Delay());          scl.x /= 1.1f;         scl.y /= 1.1f;         rock1.transform.localScale = scl;     }     else if (choice == 3)     {         scl = scissors1.transform.localScale;         scl.x *= 1.1f;         scl.y *= 1.1f;         scissors1.transform.localScale = scl;          StartCoroutine(Delay());          scl.x /= 1.1f;         scl.y /= 1.1f;         rock1.transform.localScale = scl;     }  }  static IEnumerator Delay() {     yield return new WaitForSeconds(0.1f); }


Warning: Remote Host Identification Has Changed!

After typing the command   ssh -p 8101 karaf@docker-ip onos1    I am getting the error  @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY! Someone could be eavesdropping on you right now (man-in-the-middle attack)! It is also possible that a host key has just been changed. The fingerprint for the RSA key sent by the remote host is SHA256:rV+69MOdHKanIvP41a9Xspug6am7/BV7CHVjhxKYFyM. Please contact your system administrator. Add correct host key in /home/pranav/.ssh/known_hosts to get rid of this message. Offending RSA key in /home/pranav/.ssh/known_hosts:3   remove with:   ssh-keygen -f "/home/pranav/.ssh/known_hosts" -R [172.17.0.2]:8101 RSA host key for [172.17.0.2]:8101 has changed and you have requested strict checking. Host key verification failed.   can you help me with this?


Is it possible to have a model rendered as it's seen in the 3D view in Blender?  That means, no shadows, sharp edges and everything illuminated just like the image below?


How to make a Macbook Pro lock and not sleep when connected to power?

My 2018 MacBook Pro is connected to external displays and peripherals via a Thunderbolt 3 dock.  When I step away from my desk I lock the computer by pressing ctrl+cmd+Q on my external keyboard.  This works as expected, kicking the system back to the lock screen.  However, after a few minutes of this state, the system goes to sleep, turning off the screen and requiring time to become interactive again after jabbing the power button.  How can I prevent the laptop from going to sleep once locked if connected to power? The most important aspect of this is that Touch ID stays active, so I can instantly resume work at my desk with a single touch of the sensor.


Show that $f^2(x) = (f(x))^2$ also has an essential singularity at $z_0$

I have been looking for a proof of this and I can't find anything that helps me.  Suppose that $f$ has an essential singularity at $z_0$.   Show that $$f^2(x) = (f(x))^2$$ also has an essential singularity at $z_0$.  I know that if f has an essential singularity at $z_0$ then $f$ can be represented as $$f(z)=\sum_{n=-\infty}^{\infty}a_n(z-z_0)^n$$ where $a_n \neq0$ for an infinite set on which $n<0$.  Do I continue by commuting the product of the sums?   Really need help with this thanks.


I run the following line from my bash script in order to run the script /usr/run.pl on remote machines    xargs -P "$numprocs" -I '{}' -n  1 -- perl -e 'alarm shift; exec @ARGV' -- "$timeout" ssh -nxaq -o ConnectTimeout=5 -o StrictHostKeyChecking=no '{}' /usr/run.sh < <(echo -e "$node")    but I get on the console the following standard output   Connection to 143.6.22.4 closed by remote host.  xargs: perl: exited with status 255; aborting   where I need to put the 1>/dev/null in my syntax to avoid this message?


Prove that limits from the left and right $\lim_{x\to\ a^+} f(x)= \lim_{x\to\ a^-}=L$ then $\lim_{x\to\ a} f(x)=L$.

Prove that $\lim_{x\to\ a^+} f(x)= \lim_{x\to\ a^-}=L$ then $\lim_{x\to\ a} f(x)=L$.  I started by assuming that there exists some interval $(c,a)$ such that any sequence $x_n$ in $(c,a)$ converging to $a$ has $\lim_{x\to\ a}f(x_n)$ and also some interval $(a,b)$ such that any sequence $x_n$ in $(a,b)$ converging to $a$ has $\lim_{x\to\ a}f(x_n)$.  I’m not really sure where to go from here. I want to define a sequence that spans the union of these two intervals, and then divide it into two subsequences that are less than and greater than $a$. Is that right? Any suggestions for proceeding?


How to proof $\sum_{k=1}^n k {n \choose k }=n 2^{n-1}$

I have tried trying to find a pattern but i don't believe that the right way. If you help me it would be great.


sizeof operator returns size of pointer instead of array

I'm a little confused when I run the code below:  int Maxi(int A[]) {     return sizeof(A)/sizeof(A[0]); }  int main() {     int A[5] = {1,2,3,4,5};     print("%d \n", Maxi(A));     return 0; }   And I just get the result 2. It seems that sizeof(A) turns out to be 8, which is the size of a pointer. I know this may not be a question worthy asking, but I must miss something and I just cannot figure it out right now.  But if I do this:  int main() {     int A[5] = {1,2,3,4,5};     print("%d \n", sizeof(A)/sizeof(A[0]));     return 0; }   It's all right then, and I thought it is related to the passage of value between functions, but I'm confused.  Thanks!


Why `super()` in Ursina module in Python

I imported the Ursina module to python. Ursina is game engine. You can find it here :   I was trying to learn how to use this module from the tutorials given on the website itself. I am unable to understand this part of the code. Can anyone please explain this:  from ursina import *  class Inventory(Entity):     def __init__(self):         super().__init__(             parent = camera.ui,             model = 'quad',              scale = (.5, .8),                                                         origin = (-.5, .5),                                                       position = (-.3,.4),                                                      texture = 'white_cube',                                                   texture_scale = (5,8),                                                    color = color.dark_gray                                                  )    if __name__ == '__main__':     app = Ursina()     inventory = Inventory()     app.run()   These are my specific questions:     What is super()? Why are the functionalities of super() class? What is the purpose of the condition if __name__ == '__main__':      @pokepeter P.S. Tutorials of Ursina Game Engine has a lot of typos, please provide a way to notify the same.


How an animated object moving on a plane could leave a mark on it?

I want to know how an animated object moving on a plane could leave a mark on it. In the exact way shown in this video  from 1:37 to 1:45 I need to explain how a cleaner product cleans the floor. I want to show the area where the machine is cleaning. I want to mark the floor where the machine passed through. How I can do it? In post-production for sure, but if possible (and if it's convenient) I want to avoid other softwares. I would do it on Blender. Thanks


How to keep basil leaves from turning black?

What is the best recommendation to keep fresh basil leaves from turning black after having used some of it?


What will happen having only a DC source and a diode connected in reverse?  Will the diode or the source overheat over time or something bad might happen if you let it operate like that?


Blender crashed and now when I try to open the file still crash!

I was duplicate a simple mesh with just edges and Blender crashed tried to reopen but recrash, tried to restart computer and still crash and now I have any auto save files showed, also the automatic backup file .blend1 crash. I've tried to open the file with the 2.79 blender version but still crash. I can append all object to a new file but is tedious. Is there any other thing that I can try? I have a backup but it's 3 days older!!! I can append new object on that file but still a little bit tedious remember and find the new objects Blender Version 2.90.0 (2.90.0 2020-08-31) Mac os 0.15.6 Catalina Mac book pro 16"" here is the file


Is there a way to do custom /say commands?

I've looked it up, and apparently there is not a way to. But, there's an NPC in my map where I have it "talking" with a /say command. So, is there a way to make it say something like [(NPC Name)] (Text) without mods?


What was the improvement that Maxwell did to the electromagnetic field equations and why?

What was the improvement that Maxwell did to the  and why?  I understand that he combined the main equations so that you could get a wave equation for the vectors of $\bf E$ and $\bf B$ but is there anything else?


I am learning "Function callback" and there is a segmentation fault occuring in my code?

#include <stdio.h> #include <math.h>  void swap(char* x, char* y) {   char temp;   temp = *x;   *x = *y;   *y = temp; }  int compare(char a, char b) {   if((int)a > (int)b)   {     return 1;   }   return -1; }  int bubbleSort(char *a, int n, int (*compare) (char, char)) {   int i, j;   for(i = 0; i < n; i++)   {     for(j = 0; j < n - 1; j++)     {       if(compare(a[j], a[j + 1]) > 0)       {         swap(&a[j], &a[j + 1]);       }     }   } }   void main() {   char* name = "Stackoverflow";   int i;   bubbleSort(name, sizeof(name) / sizeof(char), compare);   for(i = 0; sizeof(name) / sizeof(char); i++)     printf("%c ", name[i]); }   I have no clue about why this code is giving segmentation fault, I know the case when the segmentation fault occurs,that is, when the application tries to access the memory location out of its dedicated memory.


Is Puerto Rico considered As USA for green card holder?

Im a green card holder. I wanted to know if Puerto Rico is considered as USA state for us. Green card holder can’t be out of USA country for more than 6 months. If I stay in Puerto Rico is it considered as being in the USA?


According to this website:        The first letter indicates the file type: f means file and d means directory. But in my case I've an l. What's the meaning of this l? In my case, the file is actually a directory too.   Also some entries do not have any file type, i.e. they have a leading dash -. Does this mean that the OS does not recognise the file type?


Inequality problem involving QM-AM-GM-HM or Cauchy Schwarz inequality

Question: Prove that if $x$, $y$, $z$ are positive real numbers then the following inequality holds: $$\frac{x+y}{x^2+y^2}+\frac{y+z}{y^2+z^2}+\frac{z+x}{z^2+x^2}\leq\frac{1}{x}+\frac{1}{y}+\frac{1}{z}.$$I tried thinking of applying QM-AM, but I didn't know what variables to use. I also thought that this could be related to Cauchy's inequality, but I wasn't sure, again, of what variables to use. Any help would be greatly appreciated, thanks!


Difference between computational and statistical indistinguishabilities

What is the difference between the two notions of computational and statistical indistinguishability?


Huge white-space in latex template (springer journal)

I'm writing a paper for a Springer journal, so I downloaded Springer journal template from  and after I compiled it, there is a huge white-space on the right.   Anyone know how I can solve that?


Convergence of sequence defined with other sequence

$a_n$ is a sequence with $\lim\limits_{n \rightarrow \infty}{\frac{a_{n+1}}{a_n}}=L$, $a_n>0$.   So the task is to show that $c_n:=(a_n)^\frac{1}{n}$ converges and $\lim\limits_{n \rightarrow \infty}{c_n}=L$.  I've been working on this for hours now and don't have any useful result. Please help :)


SyntaxError: invalid syntax // SyntaxError: unexpected EOF while parsing

How do I detect text inside of this, this is HTML & this is XPath. I tried  HTML     Hello. XPath     //*[@id="liveAgentChatLogText"]/span[22]/span[2]   I tried with this but it didn't work, it said no such element found.  driver.find_element(By.XPATH, '//*[@id="liveAgentChatLogText"]//*[contains(string(.), "Hello")]')


If I root my android phone (just so I can get access to Wifi Tethering, etc.) will that erase anything on the phone (apps, data, etc.)?  Will it change anything other than the ability to run app(s) as rooted?


Identifiability of neural network models

It's quite intuitive that most neural network topologies/architectures are not identifiable. But what are some well-known results in the field? Are there simple conditions which allow/prevent identifiability? For example,    all networks with nonlinear activation functions and more than one hidden layer are not identifiable all networks with more than two hidden units are not identifiable   Or things like these. NOTE:I'm not saying that these conditions prevent identifiability (though they seem pretty good candidates to me). They are just examples of what I mean with "simple conditions".  If it helps to narrow down the question, feel free to consider only feed-forward and recurrent architectures. If this is still not enough, I'd be satisfied with an answer which cover at least one architecture among MLP, CNN and RNN. I had a quick look around on the Web but it looks like the only discussion I could find was on Reddit. Come on, people, we can do better than Reddit ;-)


Regression when the OLS residuals are not normally distributed

There are several threads on this site discussing  to determine if the OLS residuals are  normally distributed. Another way to evaluate the normality of the residuals with R code is provided in this excellent . This is another  on the practical difference between standardized and observed residuals.  But let's say the residuals are definitely not normally distributed, like in this . Here we have several thousand observations and clearly we must reject the normally-distributed-residuals assumption. One way to address the problem is to employ some form of robust estimator as explained in the answer. However I am not limited to OLS and in facts I would like to understand the benefits of other glm or non-linear methodologies.  What is the most efficient way to model data violating the OLS normality of residuals assumption? Or at least what should be the first step to develop a sound regression analysis methodology?


Prove $| \sum_{i \leq n} \frac{\mu(i)}{i} | \leq 1$

So I am trying to prove the above stated formula. I am completely new to number theory so I thank you in advance for baring with me. I start off by using the definition:  $\frac{\phi(n)}{n} = \sum_{d|n} \frac{\mu(d)}{d}$  Where $\phi$ is Eulers function, and $\mu$ is the Mobius mu function. From here, I use the Mobius inversion formula to give:  $\frac{\mu(n)}{n} = \sum_{d|n}d\frac{\phi(\frac{n}{d})}{n}\mu(d)$  Now summing $n$ up to $x$:  $\sum_{n \leq x}\frac{\mu(n)}{n} = \sum_{n \leq x}\sum_{d|n}d\frac{\phi(\frac{n}{d})}{n}\mu(d)$  Now I'm not fully sure on how I can rearrange things inside the two summations on the right hand side, so leaving things as they are; using that $\sum_{d|n} \mu(d) = 1$, if and only if $n =1$. Hence:  $\sum_{n \leq x}\frac{\mu(n)}{n} = \sum_{d|1}d\phi(\frac{1}{d})\mu(d)$  Thus $d=1$. Subbing this in:  $\sum_{n \leq x}\frac{\mu(n)}{n} = \phi(1) = 1$  I am not sure what I have missed (or done wrong) as to have an equality and not a triangle relation. Any suggestions or ideas would be greatly appreciated


Real analysis contradiction I cannot get rid of

Let $G$ be the Cantor set. It is well known that:   $G$ is perfect and hence closed. $G$ has the cardinality of the continuum. $G$ has measure zero. For any set $S \subset \mathbb{R}$ (I will not keep writing that we are in $\mathbb{R}$) we have $S \text{ is closed} \Leftrightarrow S^c \text{ is open}$. Any open set $O$ can be written as a --- in fact unique --- countable union of disjoint open intervals.   $G^c$ can thus be written as a countable union of disjoint open intervals. We now imagine this union as being superposed on the real line graphically as follows:  R: <<<----(....)---(..)--(.)---------(...)--->>>   where the (...) represents the open disjoint intervals (of differing size) composing $G^c$, and the ---  represents the remaining non-covered real numbers (that is those in $G$). Now we can cover $\mathbb{R}$ in its entirety by "collecting" the --- into disjoint closed intervals. Any one of these closed intervals might of course consist of only a single element. We now obtain:  R: <<<[--](....)[-](..)[](.)[-------](...)[-]>>>   Take the union of these disjoint closed intervals. This must be $(G^c)^c = G$. Now it is not hard to imagine a mapping from the (...)'s to the [...]'s. Just take the next (...) in line for each [...] (and do some trivial fixing at the ends). Therefore we have written $G$ as a countable union of disjoint closed sets. However, $G$ has measure zero and therefore cannot contain any closed sets other than the single element type. Hence $G$ is countable. Contradiction.  Where do I go wrong?


Unix: Is it possible to copy error output to a file while still displaying all output?

I've seen things like  command > out.txt  Sometimes appended with  2&1   But these seem to divert all output or all error streams instead of both displaying and copying the output into the file, which is what I'm trying to do. Do I have any options?


How to I merge two objects so I can move them around as if they were one object?

I've seen other questions about merging objects, usually involving deleting faces from both of them and connecting them together. But that's not what I want. I just want to be able to control many objects together, using scale, movement, etc, as if it was only one object.  Does anyone know how to do this? It seems like it should be easy but I haven't found a good explanation yet..


apalike bibliographystyle:: how to quote title of each article?

I am using apalike biblographystile in latex. I would like to quote each article title.  Currently, my latex file looks like:   \documentclass[12pt]{article}  \usepackage{apalike}  \usepackage{natbib}  \begin{document}   Here is my text followed by citation in bracket \citep{myCitation}.  \bibliographystyle{apalike}   \bibliography{myRef.bib}  \end{document}   Then my reference looks like:      Zhao, Y., Petkau, A. J., Traboulsee, A., Riddehough, A., and Li, D. K. B. (2010). Does   MRI lesion activity regress in secondary progressive multiple sclerosis? Multiple   Sclerosis, 16:434-442.    However, I want the article title to be:     Zhao, Y., Petkau, A. J., Traboulsee, A., Riddehough, A., and Li, D. K. B. (2010). "Does   MRI lesion activity regress in secondary progressive multiple sclerosis?" Multiple   Sclerosis, 16:434-442.   Is there an easy fix for this?


here is what I do right now: I create an image and fill it with some colors like so:    then I unwrap my mesh so that every face gets the color I want it to have.  However I don't like this workflow at all, I would prefer it, if I could just select colors for the faces in blender and then blender automatically generates a color map.  Somone knows if this is possible? It must be an image so I can import it to my game engine


Record screen, microphone and web camera in Ubuntu 17.10 (Wayland Session)

I want to record my screen, audio and webcam in Ubuntu 17.10.  I have tried the following software (from this thread ):   gtk-recordmydesktop: Missing web camera support xvidcap: Missing web camera support Kazam: Wont start Simple Screen Recorder: Missing web camera support VOKOSCREEN: Records only black screen Tibesti: Missing web camera support VLC: Missing web camera support, could not get it to record at all OBS: Will not start ScreenStudio: Will not start   Any suggestion for good software to do this?    After some digging I found out that if I start Ubuntu 17.10 in X Server instead of Wayland then Vokoscreen works and meets my requirements.


How do I copy hyperlinks in non-encoded format in Firefox?

When I copy the following URL from FireFox https://example.com/away.php?to=http://example.com/page/42 and then paste, I get a link like: https://example.com/away.php?to=http%3A%2F%2Fexample.com%2Fpage%2F42 How do I get the non-encoded link instead? Maybe there is a hidden option in Firefox, or a plugin. I tried searching the web, but didn't found anything. Update re. duplicate question thing: I am asking not (only) about copying text from address bar, but about copying the text from anywhere in a web page. But let's keep the link between these questions, they seem relevant.


Why do we also consider the probability of more extreme events in hypothesis testing?  I'm a beginner in statistics and I am trying to understand why do we take into consideration the probability of more extreme events when doing a hypothesis test. Let's take an example so I can explain exactly what I mean.  Let's say that we have the $2$ hypothesis:  $$H_0: \mu = 780$$  $$H_a: \mu \ne 780$$  And we set the significance level as $\alpha = 0.05$.  Now let's say we take a sample of $n = 25$ and we find that the mean of this sample is $\bar{X} = 776$. Assume that we (somehow) know the standard deviation of the population to be $\sigma = 16$.  What I understood from what I've read so far is that we assume that the null hypothesis is true. So that means that the random variable  $$\frac{\bar{X} - \mu}{\sigma_{\bar{X}}}$$  where   $$\sigma_{\bar{X}} = \frac{\sigma}{\sqrt{n}}$$  is actually the standard normal, with a mean of $0$ and a standard deviation of $1$. So out of this we calculate the $z$ statistic with the information given in the problem and get the value (after some calculations):  $$z = -1.25$$  So far, so good. Now we need to calculate the p-value. And to do so we add the probability of having $Z < -1.25$ and of having $Z > 1.25$, where $Z$ is the standard normal. This is what I don't understand. Why do we take into consideration all of that area:    Wouldn't that overestimate the p-value? I understand that we cannot consider just the observed value, but why don't we just use something like a small interval around the observed value? Why do we consider all of the events that are more extreme than the observed value? And we also consider the event that is equally likely to happen, namely $z = 1.25$, and after that we also consider the events that are more extreme than $z=1.25$ too. This is also a mystery to me. Don't we want to find the probability of that event happening, so that after finding this probability we can decide if we reject the null hypothesis or not? So if we want to find the probability of the observed value happening (given that the null hypothesis is true), then why do we also add to that the probabilities of all the events that are equally likely to happen and then all of the probabilities of the events that are less likely to happen?


How would I recreate this horizontal line in Photoshop?

I've seen variations of this idea... in HTML, the <hr /> tag creates a horizontal line that can be used as a spacing tool to separate headings, blocks of content, etc... I'd like to create such a line using Photoshop and have it look like this...   Click image for full resolution  How would I do this in Photoshop? Are there tutorials dedicated to this?


How much salt and pepper "was" or "were" added to the soup?

Which of the following is correct?   How much salt and pepper was added to the soup? How much salt and pepper were added to the soup?   In other words, should "salt and pepper" be followed by a singular or a plural verb? Please also explain why.


What should be done when someone posts the answer to their question as part of the question

Several times while browsing stack exchange sites, I've noticed that people sometimes edit their question to include the answer to the question as a separate section of the question. Example (initially posted as a question then edited to include the answer)  How do I do XYZ with ABC? Question I'm trying to do XYZ with ABC, I've tried... etc Edit: Answer I found out how to do XYZ with ABC by taking the ...  I would have thought the thing to do upon seeing this would be to edit the question to remove the answer from it and then posting the answer as an answer to the question, but would it be better to flag and let a moderator do it


Is This An Example Of Recursion (Python)

Hi I am struggling to understand exactly what recursion is, It is a requirement of the program I am writing(a snake game) and I cannot find a clear definition of what is classified as recursion. Could someone tell me if the code below is an example of this?  while True:     #recieve input     player_name = input("Enter a name between 0 and 20 characters: ")     #if length is within boundaries the loop is stopped     if len(player_name) > 0 and len(player_name) <= 20: break     #if the name is outwith the boundaries a message is printed and the loop restarts     print("Too long/short, try again.")


Why does Lang describe a field as a union and compositum of its subfields in this manner?

I am reading Serge Lang's Algebra, revised 3rd edition, and on page 226, the author makes the following definitions and observations:   If $E,F \subset L$, the compositum of $E$ and $F$ in $L$ is defined to be the smallest subfield of $L$ containing both $E$ and $F$. It is denoted $EF$. If $k \subset E$ and $\alpha_1,\dots,\alpha_n \in E$, then $k(\alpha_1,\dots,\alpha_n)$ is defined to be the smallest subfield of $E$ containing $k$ and $\alpha_1,\dots,\alpha_n$. Observe that $$ E = \bigcup k(\alpha_1,\dots,\alpha_n), $$ where the union is taken over all finite families $\{ \alpha_1,\dots,\alpha_n \}$ of elements of $E$. The compositum of an arbitrary family of subfields of a field $L$ is defined as the smallest subfield of $L$ containing all fields in the family. $E$ is finitely generated over $k$ if there is a finite family $\{ \alpha_1,\dots,\alpha_n \}$ of elements of $E$ such that $E = k(\alpha_1,\dots,\alpha_n)$. Observe that $E$ is the compositum of all its finitely generated subfields over $k$.   My question is regarding the two observations (point nos. 3 and 6). It appears to me that it is enough to take union (and compositum) over all subfields generated by a single element. For example for point no. 3, I can write $$ E = \bigcup_{\alpha \in E} k(\alpha) $$ because $E$ is clearly contained in the RHS, and each $k(\alpha)$ is contained in $E$ and hence so is the union, implying that $E$ contains the RHS. Similarly for point no. 6.  So, why does Lang emphasise to take the union and compositum over all finitely generated subfields? Is there some perspective that he wishes to emphasise that I am missing? Any help in understanding this will be appreciated.


Short story about the drawbacks of human telepathy on an alien planet

There will be heavy spoilers in my question. The plot is that a band of humans have been genetically engineered to be telepathic. Unfortunately, the engineered humans made the rest of humanity nervous, and were banished to an alien colony.  The colony does okay, despite hostile but low-tech aliens. However, things in the city begin to slowly deteriorate. Aliens suddenly appear 'out of nowhere', with the citizens discovering holes in the city walls that were clearly not new, but which the aliens are now using to infiltrate the city.  The protagonist also notes that while the telepathy trait would be expected to show up in 75% of offspring (25% having dual non-dominant genes), the actual births show almost no non-telepaths.  The story concludes by discovering that the non-telepaths notice things which the telepaths can't, because they're not being telepathically urged to ignore things (broken walls, aliens walking in their midst) which don't fit the narrative of the rest of city. In short, the normal humans see the world how it is because they're not burdened by the expectations of the whole city drowning out what their own eyes are telling them.  Any ideas what this is?


Java heap space error for stringBuilder object

class GfG {    static String encode(String str)   {     int count =1;     char c ;     StringBuilder result = new StringBuilder(200);     int i=0;     while(i<str.length()-1){         int j =i+1;         count =1;         c = str.charAt(i);         while(j<str.length() && str.charAt(j)==c  ){             count++;             j++;         }         result.append(c+""+count);         if(str.charAt(str.length()-1)!=c && j==str.length()-1)             i=j-1;         else             i=j;     }     return result.toString(); }  public static void main(String[] args) {     String res = encode("hnwnkuewhsqmgbbuqcljjivswmdkqtbxixmvtrrbljptnsnfwzqfjmafadrrwsofsbcnuvqhffbsaqxwpqcac");     if(res.equals("h1n1w1n1k1u1e1w1h1s1q1m1g1b2u1q1c1l1j2i1v1s1w1m1d1k1q1t1b1x1i1x1m1v1t1r2b1l1j1p1t1n1s1n1f1w1z1q1f1j1m1a1f1a1d1r2w1s1o1f1s1b1c1n1u1v1q1h1f2b1s1a1q1x1w1p1q1c1a1c1"))         System.out.println("yes");     else         System.out.println("no");    } }   I am getting this error and i have no clue how to deal with it . Can anyone tell me the reason and solution for this error .  Exception in thread "main" java.lang.OutOfMemoryError: Java heap space     at java.util.Arrays.copyOf(Arrays.java:3332)     at java.lang.AbstractStringBuilder.ensureCapacityInternal(AbstractStringBuilder.java:124)     at java.lang.AbstractStringBuilder.append(AbstractStringBuilder.java:448)     at java.lang.StringBuilder.append(StringBuilder.java:136)     at GfG.encode(GFG.java:18)     at GfG.main(GFG.java:28)


I would like to know if there is any difference between the captioned two methods?  string str = "14.75"; Console.WriteLine(Decimal.Parse(str)); Console.WriteLine(Convert.ToDecimal(str));   Can anyone please let me know? Thanks.


Why has no new Star Trek show been set after Voyager?

Has there been any official (from the studio or owners) reason why we haven't seen a new Star Trek show set after Voyager?   So far every new Star Trek show or movie is around The Original Series or close to an already established show:   2009 Star Trek reboot - The characters from The Original Series. Star Trek: Discovery - After Enterprise but before The Original Series. Season 2 will have Spock. The  - Features obviously, Jean Luc Picard and takes place some time after Nemesis.   Why haven't we seen a show set years after Voyager  and we follow a new crew unrelated to any series?  --  I'm aware  question asks for any material set after Nemesis, but I'm looking for an official studio reason why we haven't seen a new completely separate Star Trek series after Voyager and Nemesis.


Why keep the Precognitive badge on sites where no-one has or could have received it?

Some sites (for example SO) have obviously been around for years, and therefore no-one was around to collect this badge as it didn't exist at the time.  I was therefore wondering why it still remains on SO, and therefore why it simply isn't just just removed from the site for which it has no relevance?


I have a document which are previously compiled with regular pdflatex with \usepackage{times}, the typographic quote symbols are generated correctly as:    And once I started to use LuaLatex with:  \usepackage{fontspec} \setmainfont{Times}   The quote symbols are generated as:    How come and how to fix this? Thanks!!


I want to print the countries which which have to after ~:.  welcome~:to~:Germany welcome~:no please~:Italy welcome~:to~:Brazil welcome~:not ok~:China   Note: I do not know what will be there other than "to". It can be anything and can be changed (like no please, not ok).  I am tried using cut, awk, sed. But I am unable to figure out.   awk -F "~:" '{print $2 $NF}'   But I get output like:  toGermany no pleaseItaly toBrazil not okChina   How to filter countries other than to.  UPDATE:  Alternative solution:(Figured out with cut) :-)  grep -v "to" |cut -d ':' -f3


Is it better to use a laptop on battery or on AC power?

When I'm at home, is it better to use the laptop plugged into AC power, or with just the battery, for the overall battery life?


Add the ability to retract a reopen vote

When you vote to close a post, you can retract your close vote by re-clicking the "Close" button.  Can we have the ability to do the same with regard to reopen votes?  It should act the same way as if you were retracting a close vote, showing this popup:  Or add something relevant to reopen votes in that popup, like:  Are you sure (you cannot vote to reopen again after retracting)?


Proof of a formula for the power set of a union of two sets

I need to prove that:  $2^{A\cup B} =\left \{ X\cup Y \mid X\in 2^{A}, Y\in2^{B} \right \}$  Note that $2^{A} = P(A)$ (The power set of A).  While I can prove the Right - Left direction fairly easily, It seems very hard for me to prove the Left - Right direction. Can I get some help with that?  How do I prove that $t\in2^{A\cup B}$ makes $t\in \left \{ X\cup Y \mid X\in 2^{A}, Y\in2^{B} \right \}$?


How do I rigorously show $f(z)$ is analytic if and only if $\overline{f(\bar{z})}$ is?

I'm doing a bit of self study, but I'm uncomfortable with a certain idea. I want to show that $f(z)$ is analytic if and only if $\overline{f(\bar{z})}$ is analytic, and by analytic I mean differentiable at each point. Here $f$ is a complex valued function.  What I do is write $f(z)=u(x,y)+iv(x,y)$, where $u$ and $v$ are real functions of two variables. Then $\overline{f(\bar{z})}=u(x,-y)-iv(x,-y)$.  These two forms look very similar, in the sense the one function being differentiable should immediately imply the other is differentiable, since the only thing really changing might be a $-$ sign popping out due to the chain rule.   How can I more rigorously express that $f(z)$ is analytic iff $\overline{f(\bar{z})}$ using this? Many thanks.


How much photon energy has already been destroyed?

We get taught in school that energy can neither be created, nor destroyed. The law of energy conservation is confirmed by many processes. It is an incredibly accurate assumption for every-day life.  When we study physics at university level, we get taught the "fine-print", the exceptions to the rule. For example in cosmology we learn that the universe as a whole is expanding. The expansion affects the wavelength of photons: the wavelength gets stretched (while c remains constant), which means photons lose energy. To nothing. The energy is just gone. Experimental evidence is the cosmic microwave background (CMB), which is red-shifted to a black-body spectrum of 2.7K.  If we estimate the number of CMB photons originally produced and their energy (1eV?), subtract photon energy as observed today, then how much photon energy has been lost during the universe's expansion (in Joules)? Is it a significant amount, say, more than 1% of total hadron mass?


A rigorous mathematical proof of $1+1=2$.

Our school teacher just asked us to write the best possible proof of $1+1=2$. First thought he was joking but he was very serious about this question.  I could not even try an attempt.


Short way to link to http from https (and vice versa) using relative links

When I´m in a secure part of a web-site I´m developing (entering a specific page or folder using https), the relative links to the normal pages are automatically converted to https as well. Is there a way to tell an <a> tag to always use the http protocol instead of the https protocol (or the other way around)? I know it´s easy using the complete link ( or ), but I would like it to work with relative links (index.html, ../index.html, etc.).


I have  a select query, i would like to run it 50 times in parallel(to load test) ie. 50 independent times(a separate process).  if i run like this  for (int i=0;i<=49;i++) {  //record start time before the query  //Code that runs the select query...  //record end time after the query }   I need to test the select query for 50 times, do I need to use 50 different threads or running that query in for loop 50 times, which is the correct approach?  Is there better way to check the consumption time of the query for say 50 times ? Do i need to use threads? I am not sure how to use Threads, don't have much idea of threaded programming, any sample will help.


Please help me with the following problem( give some hints or references):  Let $X$ be a Banach space and $B(X)$ be the algebra of bounded linear operators on $X$. Suppose that $A$ and $B$ are two operators in $B(X)$ such that for every $T \in B(X)$ we have $\sigma(AT)=\sigma(BT)$. Show that $A=B$.  Here $\sigma(A)$ denotes the spectrum of $A$, i.e., the the set of all complex numbers $\lambda$ such that $\lambda I − A$ has no inverse in $B(X)$.  Thanks in advance.


To conserve screen space while editing it would be nice to compile without margins when still working on a paper. Is there any way to accomplish that?


What does AF -0.5 EV sensitivity mean? Or -3EV in Canon 6D's case?

I know that it stands for Exposure Value, so my 6D focuses in 2.5EV worse light than a 600D.  But it's relative to... what?  What makes it meaningful? What's the "base unit" for AF sensitivity?


Can someone please help. I'm wondering that if there are two people A and B, such that A' s grandparent is B's great grandparent.  Is it the case that B is A's first cousin once removed and A is B's second cousin once removed. Or is it just that they are both first cousins once removed?


For the Black-Scholes market model where the price of the riskless asset (bond) satisfies $$dB_t=rB_tdt, B_0 = 1$$ for some $r>0$ and the stock price evolves according to $$dS_t = µS_tdt + σS_tdW_t, S_0 = 1,$$ where $µ, σ > 0$ constants and $W_t$ is a (standard) Brownian motion. With fixed time horizon $T > 0$, and fixed a constant $K>0$. How can we find the price of the European call option $$G=f(S_T ) $$ where $f(x) = (x − K)_+$.  I was wondering if anyone could help me? Thanks.


Suppose that $X$ and $Y$ are independent random variables. Is $X + Y$ independent from $X$?  Intuitively I think it should be so -  because if information about $X$ gave information about $X + Y$, it should also give information about $Y$ by subtracting X - which then rephrases as, if $X$ and $Y$ are not independent, are $X + Y$ and $Y$ dependent? To answer this I would need to say something about $\sigma(X + Y)$ (in terms of $\sigma(X)$ and $\sigma(Y))$, but I am not sure how to do so.  Or is it false? I don't know.  Edit: Duplicate of


Is there a tool to view and edit ,iso files like PowerISO?

I am looking for a archive manager that will allow me to look into the contents without needing to mount it and also to add or remove contents by drag and drop style. The Windows' equivalent would be PowerISO, MagicISO or even 7-zip.  Many people suggested mounting and then copying into another directory, add/remove files, and make image again. Is that the only way?


Image of homomorphism from ideal is ideal

Let $A,B$ be rings. If $f:A\rightarrow B$ is a homomorphism from $A$ onto $B$ with kernel $K$, and $J$ is an ideal of $A$ such that $K\subseteq J$, then $f(J)$ is an ideal of $B$:  My solution: Let $a,b\in J$. Then $a+b\in J$, so $$f(a)+f(b)=f(a+b)\in f(J).$$ Also, $-a\in J$, so  $$-f(a)=f(-a)\in f(J).$$ Finally, if $c\in A$, then $$f(a)f(c)=f(ac)\in f(J).$$  We don't need the fact that $K\subseteq J$, or am I mistaken somewhere?


Read self battery voltage using PIC microcontroller

I'm working on a battery powered project where I have to constantly monitor the remaining battery level of the battery that is powering the mcu. I know it can be done using arduino and its internal vref. Now, The PIC18F26J50 I'm using also consists of a Band Gap Reference(vref). But I Don't know how to proceed or it's even possible using PIC. Is there a way to monitor the battery level in PIC using this method (or another method)?


Flag a question as being off-topic and belonging on another SE site (which is not in the suggested list)

I have , and so went to flag it as such, but after clicking "it doesn't belong here, or it is a duplicate" and "off topic," I get the following.    I think the question is more suited to Code-Review than any of the sites listed, but there doesn't seem to be an option to flag the question as "belongs on CodeReview." I am sure there is a good reason for this, and am curious to know what it is.


Why do the Elves not have more offspring?

Elves in Tolkien's legendarium are a very, very long-lived race, essentially immortal. But, yet, they don't seem to have a lot of offspring. When looking at the family trees of some of the well known Elven characters, the numbers of their offspring seem to range in what compares to humans in the here and now: i.e. low single digits. When actually, it would be easy for a 3000 year old Elf to have dozens if not hundreds of sons and daughters...   Why would Elves who live for millennia not have more offspring?   Are they not interested in raising more children after the first couple? Can they control their fertility somehow?


Is sum of two orthogonal matrices singular?

I am trying to solve following problem.      Let $A, B \in \mathbb{R}^{n\times n}$ be an orthogonal matrices and $\det(A) = -\det(B)$. How can it be proven that $A+B$ is singular?   I could start with implication:  $\det(A)=-\det(B) \Rightarrow B$ is created from $A$ by swapping two lines or columns.   But I am not sure if this implication is correct.


How can I tell how many damage dice to roll for an NPCs cantrip?

For PCs, cantrip damage increases with their total character level and not their class level ().  However, NPCs do not normally have class levels, and their stat blocks don't state a total character level.    How can I determine the number of damage dice to roll for an NPC's cantrip?   Should I use their number of hit dice as their total character level?   Should I use their stated Spellcaster level? (What if they don't have one?)   Some other method?     A couple of examples to illustrate my concern:    An Archmage (SRD p. 395) has 18d8 + 18 hit dice and is an 18th level spellcaster, so methods 1 & 2 here would produce the same result. Nezznar the Black Spider (LMOP p.59) has 6d8 hit dice and is a 4th level spellcaster, so methods 1 & 2 would produce different results.   The fact that Nezznar has more hit dice than spellcasting levels implies to me that Nezznar has, in some unspecified way, multiclassed - and that 6 would be his total character level - and the number I should use for cantrips, not 4 (his spellcasting level).   A good answer would also cover NPCs with Innate Spellcasting and no spellcasting level. See for instance:    A Green Hag (SRD. p 319) has 11d8 + 33 hit dice but no spellcasting level.


What is the best way to debug stored procedures (and write sprocs that are easier to debug)?

What are good methodologies for creating sprocs that reduce the pain of debugging? And what tools are out there for debugging stored procedures?  Perhaps most importantly, what are indications to look out for that errors are happening in a sproc and not in the code? I hope I'm not all over the board too terribly bad here. Votes for answers to any of the above. Thanks.  For what it's worth, I work in a .NET environment, SQL servers.


Landsat8 NDVI values not in the -1 to 1 range

I was trying to create an NDVI from Landsat8 OLI image from July 2013.  I ran DOS1 and TOA.  The values range up to 3.  The original files were downloaded from EarthExplorer(EE), ran on QGIS and Multispec.  The original data was downloaded again from EE and then ran only in QGIS (band calculator).    What am I doing wrong?    I switched to a landsat 5 image and i am having some problem. After the TOA and DOS1, these are the results for visible Red:'RT_LT50010862008320COA00_B3.sta' Number of Bad Lines = 0 Total Number of Pixels = 2,969,703 Histogram Summary Table First Last Line First Last Column Line Line Interval Column Column Interval 1 7251 20 1 8181 1 Channel Data Range Mean Median Standard Description Deviation 1 0.0075 to 0.6560 0.0409 0.0432 0.0294


VC 2005 error "Il mismatch between 'P1' version '20060201' and 'P2' version '20050411'"

I got one error I just can't find the problem, can someone help me or explain whats wrong? Still tried to comment out the problem or search just can't find any clues it just goes with this error:   1>Compiling... 1>option.cpp 1>Linking... 1>fatal error C1900: Il mismatch between 'P1' version '20060201' and 'P2' version '20050411' 1>LINK : fatal error LNK1257: code generation failed 1>Build log was saved at "file://c:\Users\modestas\Desktop\ybtx\code\game\gas\GameGas\Release\BuildLog.htm" 1>GameGas - 1 error(s), 0 warning(s) ========== Build: 0 succeeded, 1 failed, 12 up-to-date, 0 skipped ==========   There is no code because can't understand where this occur happened.


Why does switching to the tty give me a blank screen?

After booting to the GUI in 12.04, I attempt to move to the virtual terminal (or shell, or tty) via Ctrl-Alt-F1 (F1 through F6), and the screen remains blank. I have tried all 6 tty instances and the results are the same. Ctrl-alt-F7 brings me back to the GUI without a problem. Any thoughts?


How to unlock the Lock Screen in Android Lollipop

How can I unlock the screen lock in Android Lollipop without losing data?  I have forgotten the pattern.


sudo asks password although there is nopasswd parameter

I edited the sudoers file like below:  myuser         ALL=(ALL)       NOPASSWD: ALL newuser        ALL=(ALL)       NOPASSWD: ALL   There is no another line that contains "myuser" in sudoers file. But Linux asks password when I try sudo anything for once. It's like that only for myuser. myuser is the first user after installation. If I add a new user and give it sudo privilege as same, it can be root without password but myuser cannot.  The server runs on Azure by the way.


I have used blender for a while now and it worked perfectly, but when I opened it up today it's being very slow/laggy. When I look around in 3d view it takes forever to respond, and everything is either delayed or slow.


1.9 added a set of glider wings for us to use. Now that I have an elytra, how do I use it?


I have a layer of polygons that are pretty detailed.  I need these to be more simple.  Is there a way to make this into a polygon with just the outer boundries?


I am going through the Ubuntu installation (onto a USB) and I'm going through the standard steps, installing alongside Windows Boot Manager. Here's the page I'm on right now.    This was setup by the installation, and I have moved the divider as I like. My current selection isn't going to overwrite ANY of my old files, correct?


Repair SD card removed from phone without unmounting?

I have a Xiaomi phone and I'm using a microSD card to store photos and other data. I wanted to copy photos to PC so, with the phone turned on I just removed the sd card from the phone. Putting the card into PC doesn't work, it asks me to format it and putting it back on the phone it seems it's not recognized and when I click 'install SD' it just gives me an error. I ran Easeus Data recovery and all data seems to kinda be there so it probably just needs to run like a 'chkdsk' for android SD cards :) How can I repair this card so I can read the files normally on Windows and/or works again in Android without formatting and losing data?


I'm trying to figure out how to alter the output of a Views Block. The first image shows the situation that I'm stuck in, which obviously looks horrible, and the bottom two images are of what I would like to see, as well as the likely div plan. This is my first time working on this type of issue, so if someone has an idea of where to go, or if there is a module available for me to work with. I'm just looking for the cleanest way of getting to the output goal. Thanks!


Can the front glass on a broken lens be repaired?

I just newly broke this glass on my lens tonight. Wondering if I need to buy a new lens or if I can repair this. It is a Canon EF 85mm f/1.8 USM. This is my favorite lens to use for portraits!


Converting a word problem into an equation? Trignometry and calculus

The problem is question 3 of what I am about to download into this question. I drew a diagram of what the problem actually is, my professor has verified it's correct. I don't want an exact answer to this question, just a way to convert question 3 into an equation so that I can use programming to solve. I have software I have created that can solve for zeros of functions and minimums of functions numerically.  I am thinking that this is a problem of looking for some type of maximum because we want the biggest ladder that can fit through. Is this correct?  It's probably a nooby question, but my trignometry is pretty rusty. I have a feeling it will be blatantly obvious


Exception in thread "main" java.lang.NullPointerException How to check customers from another class (Java Object and Class)

How to check customers from another class (Java Object and Class)  I am just trying to find the customers who have motorsize = 2.0.  I created a method to figure it out which is checkmotorsize. However, it does not work. Can anyone help me about it ? Thanks      car.java         package day27;  public class Car {      String brand;     double motorSize;   }        person.java     package day27;  import java.util.ArrayList;  public class Person {          String name;         String surname;         Car car;          public static void main(String[] args) {                 Person customer1 = createCustomer("Sally", "Greg", "Mercedes", 2.0);                 Person customer2 = createCustomer("Linda", "Greg", "BMW", 3.0);                 Person customer3 = createCustomer("Joseph", "Greg", "Toyota", 2.0);                 Person customer4 = createCustomer("Midge", "Greg", "Lexus", 3.0);                 Person customer5 = createCustomer("John", "Greg", "Mercedes", 1.5);                  ArrayList<Person> listOfCustomer = createListOfCustomer(customer1, customer2, customer3, customer4, customer5);                  checkMotorSize(listOfCustomer);                 checkSurname(listOfCustomer);          }         public static Person createCustomer(String name, String surname, String brand, double motorSize) {                 Person customer = new Person();                 customer.name = name;                 customer.surname = surname;                 customer.car.brand = brand;                 customer.car.motorSize = motorSize;                 return customer;         }          public static ArrayList<Person> createListOfCustomer(Person... customer) {                 ArrayList<Person> list = new ArrayList<>();                 for (Person person : customer) {                         list.add(person);                 }                 return list;         }          public static void checkMotorSize(ArrayList<Person> list) {                 for (Person person : list) {                         if (person.car.motorSize == 2.0) {                                 System.out.println(person);                         }                 }         }          public static void checkSurname(ArrayList<Person> list) {                 for (Person person : list) {                         if (person.surname == "Greg") {                                 System.out.println(person);                         }                  }         }  }     I am just trying to find the customers who have motorsize = 2.0.  I created a method to figure it out which is checkmotorsize. However, it does not work. Can anyone help me about it ? Thanks   I am just trying to find the customers who have motorsize = 2.0.  I created a method to figure it out which is checkmotorsize. However, it does not work. Can anyone help me about it ? Thanks


Is it allowed to bring sex toys on a flight to Singapore?

I'll be taking a flight from Tokyo to Singapore. If I take a "pocket pussy" (artificial vagina) as carry on, will it be confiscated? Also will it be removed from my bag? I'm traveling with my family and don't want any embarrassment.


I cant find my Minecraft Screenshots anywhere, i have looked at %appdata%/.minecraft Does anyone else know a way i can view them?

I cant find my screenshots folder anywhere, its not in the app data folders, I am just wondering if there is any other way to view my screenshots or if I could somehow get my screenshots folder back to where its supposed to be. I have already tried to look in all my other folders on this computer, but its still no where to be found. I would just like to know if anyone could help resolve this problem as I would like to view my photos that I took on mine-craft a year ago.


Equivalence between Elastic Net formulations

According to Hastie's , the elastic net has two equivalent formulations:  $$\hat{\beta} = \underset{\beta}{\operatorname{argmin}} \left\{ \sum_{i=1}^N\left(y_i-\sum_{j=1}^p x_{ij} \beta_j\right)^2  + \lambda_1 \sum_{j=1}^p |\beta_j|+ \lambda_2 \sum_{j=1}^p \beta_j^2 \right\}$$  and  $$\hat{\beta} = \underset{\beta}{\operatorname{argmin}} \left\{ \sum_{i=1}^N\left(y_i - \sum_{j=1}^p x_{ij} \beta_j\right)^2\right\} \;\text{ s.t. } \;(1-\alpha)\sum_{j=1}^p |\beta_j| + \alpha\sum_{j=1}^p \beta_j^2 \leq t$$  where $\alpha = \frac{\lambda_2}{\lambda_1 + \lambda_2}$  My question is how to prove this equivalence formally. Ridge regression and the lasso also have these two possible formulations, but I could not find any reference where this equivalence is proven. A similar question I found in CrossValidated is this one     but I'm unable to understand Tristan's explanation. I have some understanding of Lagrange optimization theory, and I guess the answer is around those lines, but since all the papers treat the equivalence as obvious I would like to find a proper reference where this is explicitly demonstrated.


Section mark styling and page number style

Im quite new to LaTex but i am willing to learn how to style my own Thesis instead of just copy and paste some code from a template.   Now im facing a problem. I would like to style my thesis similar to that example:     Sure, the CleanThesis Template can do that, but i dont really want to include all the other code which i maybe dont neeed at all.   Therefore i would like to ask you, how i can implement the red marked behaviour. In CleanThesis the big "Section" Numbers are in fact Chapter numbers. Since my thesis is based on the "article" class i dont have chapters at all. Is it also possible to style the main "sections"   \section{some Section}   according to my example? Or is it only possible for Chapters?  Thank you :)  Edit 1: It is also important for me to learn how to put the subsection number (here 2.1) beneath or "outside" of the textblock  Edit 2:  Now i have changed my class to scrreprt to include koma script.  Then i added the following:   \definecolor{chaptercolor}{rgb}{0.36,0.73,0.82}  \setkomafont{chapter}{\normalfont\color{chaptercolor}\Huge} \setkomafont{chapterprefix}{\Large} \renewcommand*{\raggedchapter}{\raggedleft} \renewcommand*{\chapterformat}{%     \MakeUppercase{\chapappifchapterprefix{}}%     \rlap{\enskip\resizebox{!}{2.2cm}{\thechapter} \rule{1.5mm}{4cm} }% }  \RedeclareSectionCommand[beforeskip=8mm,afterskip=10mm]{chapter} \renewcommand*\chapterheadmidvskip{\par\nobreak\vspace{10pt}}   With the above code i got this:     How can i make the Text that it floats to left and define its margin from the chapter number? and how can i change the position of the line to the left side of the number?  Thanks


Drawing "bus width"-like markers with number on arrows

I'm trying to draw arrows with / marks and numbers like in the following picture:    My current solution looks like this:  \begin{tikzpicture}     [         inverter/.style={rectangle,draw,inner sep=2pt,minimum size=6mm},         dot/.style={circle,inner sep=0pt,minimum size=0.5mm,draw,fill=black}     ]     \node (x) at (0,0) {$x$};     \node (delta) at (1,0) [shape=rectangle,draw,minimum height=18mm,minimum width=6mm] {$\delta$};      \node(ah)     at ( 2,  0.5) [inverter] {$a_h$};     \node(al)     at ( 2, -0.5) [inverter] {$a_l$};      \draw [->] (x) -- (delta);      \draw [->,dashed,dash pattern=on 1pt off 1pt] (delta.58.75) -- (ah);     \node at ($ (ah) - (0.55, 0) $) {\scriptsize /};     \node at ($ (ah) - (0.5, 0.2) $) {\tiny 4};     \draw [->,dashed,dash pattern=on 1pt off 1pt] (delta.-58.75) -- (al);     \node at ($ (al) - (0.55, 0) $) {\scriptsize /};     \node at ($ (al) - (0.5, 0.2) $) {\tiny 4}; \end{tikzpicture}   which is pretty hacky and doesn't look nice. I tried strike out shapes but found the line to be much too long. However, positioning a / and a number manually seems like a pretty bad solution to me. I've seen a similar question that revolved around striking out lines or arrows, but without any numbering. Any input would be most welcome.


How to remove duplicate values from a multi dimensional array for specific key in php

I searched for solutions on here but didn't find one for my use case. I have a big array which is built like this example: Array (     [0] => Array         (             [Template] => page.html5         )      [1] => Array         (             [Template] => page2.html5         )      [2] => Array         (             [Template] => page.html5         )      [3] => Array         (             [Template] => page2.html5         )      [4] => Array         (             [Template] => page.html5         )      [5] => Array         (             [Template] => page2.html5         )      [6] => Array         (             [id] => 27             [table] => tl_custom             [type] => text             [data] => Array                 (                     [fragment] => example                     [previewId] => 1                     [isActive] => 1                 )          )  )  I would like to remove all duplicate values for the array key "Template", but besides that I want the array to stay the way it is. So afterwards my Array should look like: Array (     [0] => Array         (             [Template] => page.html5         )      [1] => Array         (             [Template] => page2.html5         )     [6] => Array         (             [id] => 27             [table] => tl_custom             [type] => text             [data] => Array                 (                     [fragment] => example                     [previewId] => 1                     [isActive] => 1                 )          )  )  Is there a way to achieve this without using lots of memory? Thanks for your answers :)


where does lspci gather its information from?

In  I found "[The   latest   version    of   this   document   ". There I says: "… lspci is a synonym for cat /proc/pci".  Which isn't the case here, on a Crunchbang 10 system (Debian based). No such directory. I do get the basic idea and, as far as I  know, the content of proc is (mainly) created during runtime. (Wrong?). This made me curious:  Question: Where does lspci gather it's information from? And where is this documented? (Where did I miss something?)    Another difference I found: In kernel.org's documentation, under "Table 1-5: Kernel info in /proc"      pci     Deprecated info of PCI bus (new way -> /proc/bus/pci/, decoupled by `lspci)


Integral solutions of hyperboloid $x^2+y^2-z^2=1$

Are there integral solutions to the equation $x^2+y^2-z^2=1$?


Prove: The set of interior points of any set $A$, written int($A$), is an open set.  Let $p\in$ int($A$), then by definition $p$ must belong to some open interval $S_{p}\subset A$. Now since we know that the real line itself is open then $S_{p}\subset \mathbb{R}$. Now suppose we pick some $q\in A$. I want $q\in$ int($A$).   I am stuck here I am not sure if my logic is correct, any suggestions would be greatly appreciated.    Definition of interior: Let $A$ be a set of real numbers. A point $p\in A$ is an interior point iff $p$ belongs to some open interval $S_{p}$ which is contained in A: $p\in S_{p}\subset A$  Definition of open: A set $A$ is open iff each of its points is an interior point


How to setup a restricted SFTP server on Ubuntu?

I would like to know how to set up root, sudo, sftp-only user accounts which won't be required public key authentication at log in. I would also like to know how to set up sftp-only users' home directories where they can't access upper level other directories.


What is an "integration script" and why would I want one?

When I navigate to Launchpad in Firefox, a pop-up appears:    I think, despite its failure to form a coherent question, it's trying to ask me if I want to install an "integration script" called "unity-webapps-launchpad".  Sadly, it does not provide me with enough information to make an informed decision, nor does it refer me to a source where I can learn more about it.  The top result in my web searches on the topic is my own . While this cyclical phenomenon provides a brief source of amusement, it is ultimately unhelpful. So, once again, I've come to Ask Ubuntu for a nudge in the right direction.  What is this thing?


schengen visa refused from french embassy pakistan

my relative and I, both currently unemployed but starting school/careers soon, had decided to make a short term trip to Europe before we get on to our lives.  I previously have one visa refusal and one removal order from canada. Basically I was in canada, working, when my then visa got refused and by law I had 90 days to restore my status. I stupidly applied for incorrect visa, which I found about much later on ( probably should have consulted with some lawyer first ) so when the restore application got refused, that automatically meant i have to leave the country so that counted as ' removal '. During this time I obeyed all laws and regulations and conditions of my stay and did not do anything illegal. anyways i left the country within 30 days. I show all of this in my application in form of explanation letter. I have applied for PR for canada as well, however since at the time of my schengen visa i had not officially submitted all documents, i couldnt show them any prove of that so i left that as i did not have any acknowledgement letter of that.   My relative also has one visa refusal from canada. he once applied for study permit and even got call for medical. due to family emergency, he decided not to continue the application. unknowingly to him, if u dont respond to request for medical, couple of weeks later that automatically counts as refusal.  I am in between jobs so I put occupation as unemployed/travelling. My relative is joining university in canada in May for which he has applied for visa. He is just waiting for his visa for that so he put occupation student.  Anyway we submitted our application with A to Z all documents at french embassy in pakistan. We indicate our refusals, submit refusal letters, explaantion letters, my brother shows his canadian university offer letter that he plans to leave schengen visa because he has to go to university, all that stuff.  today we got sad news that our visas have been refused for the following reason:  Your intention to leave the territory of the Member States before the expiry of the visa applied for could not be ascertained.  Is our current situation most likely reasons for visa refusal that we had past visa refusals from canada? was it a mistake to be truthful about that in our applciations?  Is there a way we can ask them to give us specific reasons as to why our visa got refused?   We just wanted to enjoy have a good summer time in europe.  we just want to know what exactly prompted them to refuse our visas.


Identical MAC addresses on Network updated

I have a network wired connected heatpump with a static IP address on my LAN, my son's Nintendo Switch has an identical MAC address. Even though it connects via Wi-Fi from an access point, it refuses to connect to the internet. I can get it to see the local network and it appears briefly in the access point log but will not connect out to the internet. It would seem impossible to alter either bit of kit's MAC address.  Any ideas how I can get them working?  I have turned off MAC filtering but all that achieved was enabling the Switch to connect to the network, it could not make the next step to the internet.  Update: The MAC in question is 98:e8:fa:53:c1:01 and is the same on both the Nintendo Switch and the Nibe Heat pump. I keep all my permanent devices locked on static IP addresses (From a reserved list) and hardwired back to the router, there is a uplink to my wireless Access point (Ubiquiti) which then serves both main and guest wifi networks with its own DHCP server function using a specified range not used anywhere else on my networks. I had thought that giving the Switch its own static IP address might work but although it appears in the wifi log it refuses to connect and it looks like the MAC id takes precedence over the static IP address I assigned it.   @Tonny, the Vlan option might work as the Ubiquiti has this capability , although I have never explored it before - so will give that a try, wish me luck. Otherwise I agree with you about changing the NSwitch although it is over three months since we got it (this Christmas was the first time we tried the internet connected aspect of it) so Currys may not play ball : (Sorry for the duplication of the question but the original was not showing up on my account and was very hard to search for every time).


What does ** (double star/asterisk) and * (star/asterisk) do for parameters?

In the following method definitions, what does the * and ** do for param2?  def foo(param1, *param2): def bar(param1, **param2):


How do I explain zero knowledge proof to my 7 year old cousin?


Calculating impact force for a falling object?

Good evening, I'm trying to calculate what kind of impact force a falling object would have once it hit something. This is my attempt so far:  Because $x= \frac{1}{2} at^2$, $t=\sqrt{2x/a}$ $v=at$, therefore $v=a \sqrt{2x/a}$ $E_k=\frac{1}{2} mv^2$, so $E_k=\frac{1}{2} m(2ax)=m \cdot a \cdot x$ Since $W=E_k=F_i s$, $F_i=E_k/s=(m \cdot a \cdot x)/s$  For an object weighing about as much as an apple, $0.182$ kg, falling $2.00$ m straight down and creating a dent of $0.00500$ m, this would result in:  $$F_i=(m \cdot a \cdot x)/s$$  $$F_i=(0.182 \cdot 9.81 \cdot 2.00)/0.00500=706 \, \text{N}$$  Does this make any sense? I wouldn't be surprised at all to find out I'm missing something here.   Any input would be appreciated,   thanks in advance!


I'm unable to watch HBO Nordic on my laptop using Ubuntu.  I previously used ubuntu 14.04 32-bit but was unable to get firefox to play HBO. When you played a movie I could only see the loading screen.  Tried the solutions in  without any luck. So I ended up upgrading to 16.04 LTS 64-bit because I read somewhere that Chrome would play HBO.  Once upgraded and with Chrome installed I ran into the same problem.  I keep reading on forums about the issue and read about the HAL package which presumably was the way to go. Nope. same error.   The pipelight plugins never appeared amongst the firefox plugins and reading on hal you could test that it works by going to , and entering  but there I only receive "Loading Flash Access License".  Does anyone have any suggestions?


Definition of 'term t is free for v in $\phi$' in predicate logic

I'm trying to get my head around the expression "term $t$ is free for variable $v$ in formula $\phi$". This is defined in many sources as:   (Def 1)"$t$ is free for $v$ in $\phi$ if there is no variable $v_1$ in $t$ such that $v$ has a free occurrence in the scope of a quantiﬁer $\forall v_1$ or $\exists v_1$.   In other sources it is introduced (informally) as:   (Def 2)"If no variable capture occurs during the substitution of $t$ into free occurrences of $v$ in $\phi$, then $t$ is free for $v$ in $\phi$."  Question 1: After substituting $t$ into every free occurrence of $v$ in $\phi$, if every variable of $t$ is a free variable in the resulting formula, then $t$ is free for $v$ in $\phi$. Is this correct? I don't understand why.  Question 2: Consider the formula $\phi : \forall v, \  (v \doteq v_1)$. Is $v_1$ free for $v$ in $\phi$? According to definition 1, it is not, as $(v \doteq v_1)$ has a free occurrence of $v$. However, according to definition 2, it is, as $\phi[v_1/v] = \forall v, \  (v \doteq v_1)$ (as we are only concerned with free occurrences of $v$ when doing substitution), and no variable capture has occurred. Where have I gone wrong?   Is (non-appearing in $\phi$) variable $v_2$ free for variable $v_3$ in $\phi$? There is no variable capture after substitution, because substitution $\phi[v_2/v_3]$ in this case does nothing.  Question 3: Is the following true? $v$ is free for $v$ in $\psi$, no matter what the formula $\psi$ is.   Question 4: $v$ is not a free variable of sentence $\theta$ and $v$ is a free variable in $\phi(v)$.  Then $v$ is free for $v$ in the formula $\theta\to \phi(v)$.  I'm finding this concept so confusing. Can anyone help clarify this? Thanks.


What is the meaning of $p(y|x;\theta)$ and $p(x;\theta)$ and $p(x,y|z)$?

I saw these in a machine learning notes. and like to know the meaning of them? also the formula of them?


Is a UK Transit visa required by an Indian national travelling from Ireland to India via LHR?

I’m an Indian passport holder with a D category long-stay student visa (Stemp2). I’m going to India via London Heathrow with two hours layover. My .  Will I need a UK Transit visa?


Simple question: how do you guys develop (write) a landing page and test it? Publishing and waiting for updating url and refreshing?  Isn't that a little bit "horrible"?  Any idea of developing and testing with cloudpages?  How can I see errors in my ampscript code when my landing url throws a 500 error?  Thank you!


Accessing data on a mounted phone takes FOREVER

I have a Smasung A40, and when I connect it via MTP to get some data off of it, it takes AGES. When I connect it first and attempt to open the phone, it takes a solid 30 seconds before any folder appear, and the same goes if I open any subdirectory. Accessing files also is not particularly fast (like 10s to open a picture) My google search turned up no results. I am also using a short, USB 3-capabe cable, but the problem still exists, no matter which cable or which USB port I use. I am running Ubuntu 20.04 LTS with all updates installed. Any idea on what could cause this issue?


Given $X$ and $Y$ are independent N(0,1) random variables and $Z = \sqrt{X^2+Y^2}$ from the marginal pdf of $Z$

Let $X$ and $Y$ be independent $N(0; 1)$ random variables. Let $Z = \sqrt{X^2+Y^2}$.  (a) Derive the marginal pdf of $Z$ and then using the marginal pdf to compute ${\rm E}[Z^2]$  (b) Can you propose a different way other than that in (a) to compute ${\rm E}[Z^2]$  (c) Compute ${\rm E}[Z]$.  This is the whole question that I was asked. I can do (c) but I don't know how to find the marginal pdf of $Z$ with the given information and can't seem to find any formulas. Any help would be appreciated.


Extensions disappear when I close and open Google Chrome

I am running the latest version of Google Chrome 23.0.1271.97 (Official Build 171054) m on Windows 7. Any new extension I install simply disappears (not disabled, total disappearance) once I close and re-start Google Chrome. This is not happening to any of my old extensions; they stay there across Chrome re-starts.  I tried everything Google Help suggested:   I created new user profile by renaming the Defaults folder I checked for any permission change that the extensions might have undergone. This is not the case. I am not running in developer mode.   This happens when I close all instances of Google Chrome. Even if one instance of Chrome is running, this doesn't happen. But I can't have an instance of Google Chrome always running.  I even reported the issue to Google Chrome team to no avail and  is offline. And I skimmed through many threads opened for the same issue only to find souls like me. Stack Exchange is my last resort.


Do I need a Transit visa to fly Delhi-Zurich-Dublin-St. Johns (Canada)?

I have journey to make from Delhi to Canada on a Canadian Student visa. I am an Indian Passport holder. My itinerary is Delhi to Zurich to Dublin to St. John's (Canada).   As far as I know Zurich (Switzerland) is a schengen country and Dublin (Ireland) is a non-schengen country.   My query is do I need a transit visa for the 8 hours (at Zurich) and 2 hours (at Dublin) layover periods in these countries?  Thanks


I'm looking to cite the source of a definition, but there seems to be a bug. An example of something I'm looking to type: \begin{definition}[\cite[Definition 1.4.2]{Hilbert10}]    content \end{definition}  It seems that the right bracket after Definition 1.4.2 is interfering with the right bracket after {Hilbert10}. Latex thinks I'm misusing \cite, but it's just not reading the entire line.


I don't really understand this equation and was wondering if someone could help.  The book says      when the restoring force is directly proportional to the displacement the oscillation is called .    and this next part confuses me      the acceleration $a =d^2x/dt^2 = -kx/m$ so it makes sense since the second derivative of position is acc.    but how do they get that last expression?


Multiple hidden input with same name, always retrieve the last input

foreach ($graphEdge as $graphNode) {     echo       "
" .         "<input type='radio' name='fb_profile' class='form-check-input' value='".$graphNode['name']."'>" .         "" .          "" .          $graphNode['name'] . '' .        "
";      echo "<input type='hidden' name='fb_access_token' value='" . $graphNode['access_token'] . "'>";     echo "<input type='hidden' name='fb_id' value='" . $graphNode['id'] . "'>";     }   As the title suggests, I have 3 hidden inputs named 'fb_id' that when I POST in a form will always retrieve the last hidden input yet fb_access_token will always POST correctly.


I have a link,   When that link is opened in Safari on either MacOS or iOS, it gives me an "unknown error" (NSURLErrorDomain: -1) and fails to load.  It works without a problem in Chrome on MacOS.  Any wisdom?