When I'm reviewing items I sometimes come across answers like this:     Here's what you are looking for: www.domain.com/resource.aspx   How should one handle these? By adding a comment?
I have often wondered at the practice on Stack&nbsp;Overflow, Server&nbsp;Fault, and the other sites where someone will ask a question and an answer will come in that says Look here: http://link elsewhere. Rarely will the link have exactly the answer necessary -- often it's an entire article -- yet these answers get voted up.  Why is that, exactly? I realize this is subjective, but my own thoughts are that one should try and give the answer (even if the answer is 'no, it can't be done' or 'no, I don't think it can be done' -- very different answers) and then if you have a link that explains it, go ahead and post it within the answer.  What does the community think about this?     For more information, see  in the .
My question is specifically for badges in a particular tag. I've heard that the rules have been changed.  How and when can one get bronze, silver and gold badges for a specific tag, say ? What are the new rules governing these badges? In Drupal 8 you can load an entity with:  $node = \Drupal::entityManager()-&gt;getStorage('node')-&gt;load(123);   This looks for the entity definitions and finds that node is defined by Drupal\node\Entity\Node - so (I guess) Drupal\node\NodeStorage will instantiate a new Drupal\node\Entity\Node instance.  What I'd like to achieve is subclassing Drupal\node\Entity\Node and being able to instantiate this subclass when it's appropriate. For example if I have a node bundle article, there would be a class:  namespace Drupal\my_module\Entity\Article; class Article extends Drupal\node\Entity\Node { }   And I'd call:  $node = \Drupal::entityManager()-&gt;getStorage('node_article')-&gt;load(123);   And the return would be my Article subclass.  I can achieve this by creating a new entity type and wiring it back to another existing entity definitions, for example the node-article example would be this class:  namespace Drupal\my_module\Entity; use Drupal\node\Entity\Node; /**  * @ContentEntityType(  *   id = "node_article",  *   label = @Translation("Content"),  *   bundle_label = @Translation("Content type"),  *   handlers = {  *     "storage" = "Drupal\node\NodeStorage",  *     "storage_schema" = "Drupal\node\NodeStorageSchema",  *     "view_builder" = "Drupal\node\NodeViewBuilder",  *     "access" = "Drupal\node\NodeAccessControlHandler",  *     "views_data" = "Drupal\node\NodeViewsData",  *     "form" = {  *       "default" = "Drupal\node\NodeForm",  *       "delete" = "Drupal\node\Form\NodeDeleteForm",  *       "edit" = "Drupal\node\NodeForm"  *     },  *     "route_provider" = {  *       "html" = "Drupal\node\Entity\NodeRouteProvider",  *     },  *     "list_builder" = "Drupal\node\NodeListBuilder",  *     "translation" = "Drupal\node\NodeTranslationHandler"  *   },  *   base_table = "node",  *   data_table = "node_field_data",  *   revision_table = "node_revision",  *   revision_data_table = "node_field_revision",  *   translatable = TRUE,  *   list_cache_contexts = { "user.node_grants:view" },  *   entity_keys = {  *     "id" = "nid",  *     "revision" = "vid",  *     "bundle" = "type",  *     "label" = "title",  *     "langcode" = "langcode",  *     "uuid" = "uuid",  *     "status" = "status",  *     "uid" = "uid",  *   },  *   bundle_entity_type = "node_type",  *   field_ui_base_route = "entity.node_type.edit_form",  *   common_reference_target = TRUE,  *   permission_granularity = "bundle",  *   links = {  *     "canonical" = "/node/{node}",  *     "delete-form" = "/node/{node}/delete",  *     "edit-form" = "/node/{node}/edit",  *     "version-history" = "/node/{node}/revisions",  *     "revision" = "/node/{node}/revisions/{node_revision}/view",  *   }  * )  */ class Article extends Node { }  // Results my Article sub type. $node = \Drupal::entityManager()-&gt;getStorage('node_article')-&gt;load(123);   This works fine (as much as I can see); however, it smells. It adds a new entity type, which is not true, and might cause other troubles in the future.  How do I define a subclass for an entity bundle so that loading the entity would return an object of that class? Featured On Meta section doesn't list MSE posts on meta sites How do I remove duplicate items from an array in Perl? I have an array in Perl:  my @my_array = ("one","two","three","two","three");   How do I remove the duplicates from the array? I have a SQL script that creates a package with a comment containing an ampersand (&amp;). When I run the script from SQL Plus, I am prompted to enter a substitute value for the string starting with &amp;. How do I disable this feature so that SQL Plus ignores the ampersand? For all types of derivative works, namely:   Movies Novels Comic books Other written works (including RPG materials) Cartoons Video games Derivative movies (such as the infamous Ewok movies and even more infamous )   According to what rules does something become "canon" and who is responsible for the evaluation of a published work? How can I start learning about political philosophy? I'm interested in learning about political philosophy. What are the best ways to start? Are there any websites for beginners? Are there any books such as the "For Dummies" series? Are there any audio or video introductions to familiarize myself with the terminology? What is the definition of a "feature map" (aka "activation map") in a convolutional neural network? Intro Background Within a convolutional neural network, we usually have a general structure / flow that looks like this:  input image (i.e. a 2D vector x)   (1st Convolutional layer (Conv1) starts here...)  convolve a set of filters (w1) along the 2D image (i.e. do the z1 = w1*x + b1 dot product multiplications), where z1 is 3D, and b1 is biases. apply an activation function (e.g. ReLu) to make z1 non-linear (e.g. a1 = ReLu(z1)), where a1 is 3D.   (2nd Convolutional layer  (Conv2) starts here...)  convolve a set of filters along the newly computed activations (i.e. do the z2 = w2*a1 + b2 dot product multiplications), where z2 is 3D, and and b2 is biases. apply an activation function (e.g. ReLu) to make z2 non-linear (e.g. a2 = ReLu(z2)), where a2 is 3D.    The Question The definition of the term &quot;feature map&quot; seems to vary from literature to literature. Concretely:  For the 1st convolutional layer, does &quot;feature map&quot; corresponds to the input vector x, or the output dot product z1, or the output activations a1, or the &quot;process&quot; converting x to a1, or something else? Similarly, for the 2nd convolutional layer, does &quot;feature map&quot; corresponds to the input activations a1, or the output dot product z2, or the output activation a2, or the &quot;process&quot; converting a1 to a2, or something else?  In addition, is it true that the term &quot;feature map&quot; is exactly the same as &quot;activation map&quot;? (or do they actually mean two different thing?)  Additional references: Snippets from :  *The nomenclature is being used loosely here. In particular, I'm using &quot;feature map&quot; to mean not the function computed by the convolutional layer, but rather the activation of the hidden neurons output from the layer. This kind of mild abuse of nomenclature is pretty common in the research literature.   Snippets from :  In this paper we introduce a visualization technique that reveals the input stimuli that excite individual feature maps at any layer in the model. [...] Our approach, by contrast, provides a non-parametric view of invariance, showing which patterns from the training set activate the feature map. [...] a local contrast operation that normalizes the responses across feature maps. [...] To examine a given convnet activation, we set all other activations in the layer to zero and pass the feature maps as input to the attached deconvnet layer. [...] The convnet uses relu non-linearities, which rectify the feature maps thus ensuring the feature maps are always positive. [...] The convnet uses learned filters to convolve the feature maps from the previous layer. [...] Fig. 6, these visualizations are accurate representations of the input pattern that stimulates the given feature map in the model [...] when the parts of the original input image corresponding to the pattern are occluded, we see a distinct drop in activity within the feature map. [...]  Remarks: also introduces the term &quot;feature map&quot; and &quot;rectified feature map&quot; in Fig 1.  Snippets from :  [...] One dangerous pitfall that can be easily noticed with this visualization is that some activation maps may be all zero for many different inputs, which can indicate dead filters, and can be a symptom of high learning rates [...] Typical-looking activations on the first CONV layer (left), and the 5th CONV layer (right) of a trained AlexNet looking at a picture of a cat. Every box shows an activation map corresponding to some filter. Notice that the activations are sparse (most values are zero, in this visualization shown in black) and mostly local.   Snippets from   [...] Every unique location on the input volume produces a number. After sliding the filter over all the locations, you will find out that what you’re left with is a 28 x 28 x 1 array of numbers, which we call an activation map or feature map. Sign of Work and potential energy in electrostatics Conceptual question:  Suppose we have a configuration of point charges. If the potential of the energy of the system is negative, this means work is positive.   I'm kind of rusty with my mechanics, does the fact that the work is positive mean that to arrange the configuration you have to do work against the electric field? I.e. supply energy via some external force?  In terms of electrostatics, is there a general way of interpreting the sign of potential energy and work? Modified Hamilton's Principle overconstraining a system by imposing too many boundary conditions In Hamiltonian Mechanics, a version of Hamilton's principle is shown to evolve a system according to the same equations of motion as the Lagrangian, and therefore Newtonian formalism. In particular, letting $\delta$ indicate a variation of the path through phase space, $$ \delta \int_{t_1}^{t_2} \big(p_i \dot{q}_i - H(p_i,q_i,t)\big)dt = 0 $$ is shown to generate the same motion equations as those found by the Legendre transform of the Lagrangian equations of motion. Essentially, when we calculate the Euler-Lagrange equations for the above integrand, we find $$ \dot{p}_i + \frac{\partial H}{\partial q_i} = 0\text{, } \dot{q}_i - \frac{\partial H}{\partial p_i} = 0. $$ Now, since these are both first-order equations of motion, we require $2n$ boundary conditions to obtain a solution, where $n$ is the number of particles. This is perfectly consistent with the Lagrangian formalism which had $2n$ boundary conditions due to its $n$ distinct second-order motion equations.   An important thing to note is that since $p_i\dot{q}_i - H(p_i,q_i,t)$ contains no $\dot{p}_i$ dependence, the variation in $p_i(t)$ need not be zero at the endpoints of the path. This is not the case with $q_i(t)$ because the $\dot{q}_i$ dependance results in the appearance of boundary terms that must be set to zero in order to obtain the motion equations.  Now, as far as the boundary conditions are concerned, this makes sense. For the path to be uniquely specified given Newtonian mechanics, we require $2n$ boundary conditions. These can either be the usual Newtonian choice of initial positions and velocities/momenta, or they can be the initial and final positions. Both are perfectly acceptable mathematically speaking. If we were required, in the modified Hamilton's principle variation, to enforce that the variations in the momenta also be zero at the initial and final times, this would mean $2n$ additional boundary conditions, which would generally over constrain a Newtonian system.   However, my confusion is this: when textbooks (Goldstein in particular) consider generating functions, they require that the integrand be invariant to the addition of a total time derivative of a function $F(q_i,p_i,t)$ of the phase space coordinates. However, adding such a function will in general add some $\dot{p}_i$ dependence to the integrand, which will then add boundary terms to the equations of motion unless we require that the $p_i(t)$ variations be zero at the boundaries. This is fine as far as it goes. We can always define the variation however we like. The point is just that it spits out the right motion equations at the end of the day. But my confusion lies in how this doesn't generally over constrain the system. If we specify all the positions and momenta at both the initial and the final times, might not the required path to connect those points in phase space be non-Newtonian? Does this only matter if you're actually trying to use the stationary action principle to find the paths, rather than just using it to find the motion equations? Is smell a bad way of determining whether meat is still good? Word or idiom for someone holding (seemingly) contradictory views I think some good words would be conflicted, or confused. As an example of context, think of someone who believes in freedom of speech, but, at the same time, they would support banning comedians who make jokes about certain issues that person cares about. How to make ssh log in as the right user? I use ssh on a variety of machines, mainly linux. Accounts on these machines vary in naming scheme: if my name is First Last, then I have accounts: first, flast, last_f, lastf, and sometimes I need to log in as root. For each machine I use, I would like the openssh client to know which account to use when I don't specify on the command line.  So the question is: How do I make ssh server Do The Right Thing when a username is not specified? Show $d_{1}(x_{n},x)\rightarrow{0}$ if and only if $d_{2}(x_{n},x)\rightarrow{0}$. Let $X=(0,\infty)$. Define two metrics on $X$ by   $d_{1}(x,y)=|x-y|$ and   $d_{2}(x,y)=|x-y|+|\frac{1}{x}-\frac{1}{y}|$   for all $x, y \in{X}$.   Let $(x_{n})$ be a sequence in $X$ and $x\in{X}$.   Show  $d_{1}(x_{n},x)\rightarrow{0}$ if and only if $d_{2}(x_{n},x)\rightarrow{0}$.  Note: $d_{1}$ and $d_{2}$ are then said to be equivalent metrics on $X$.  Since $d_{1}$ and $d_{2}$ are equivalent metrics, will it be sufficient to show $c*d_{2}(x,y)\leq{d_{1}(x,y)}\leq{C*d_{2}(x,y)}$?  So far I have the following: $d_{1}(x,y)=|x-y|\leq{|x-y|+|\frac{1}{x}-\frac{1}{y}|}=d_{2}(x,y)$. Therefore, $d_{1}(x,y)\leq{C*d_{2}(x,y)}$ where $C=1$. Is there a $c$ that would satisfy the left-hand side of the inequality?  Any help would be appreciated. (this is not homework) This or That person Since my previous questions were not answered I will try to ask again more precisely.  I previously had the Nvidia driver installed and working correctly.  Then the ubuntu software update did something which broke it.  In fact, it completely de-configured it so that the standard display driver is used when the computer reboots.  I would like to re-enable the existing Nvidia  driver without re-installing the Nvidia driver.  How do I do that?  This machine is no longer connected to the internet.  NOTE: I am not asking how to disable automatic updates in this question.  I asked that elsewhere (and it wasn't answered).  NOTE: I am not asking how to stop the Ubuntu software updater from breaking the Nvidia driver the next time it updates the system.  That would be nice to know, but I asked that already and did not receive the correct answer either.  NOTE: Please don't make this as duplicate simply because someone else asked a question about Ubuntu and the software updater.  Try to read the actual question and see how it's different and try to realize how annoying it is when users have to spend hours of their own time to correct the problems that other people causing by incorrectly designing software updaters. Detach (move) subdirectory into separate Git repository I have a  repository which contains a number of subdirectories. Now I have found that one of the subdirectories is unrelated to the other and should be detached to a separate repository.  How can I do this while keeping the history of the files within the subdirectory?  I guess I could make a clone and remove the unwanted parts of each clone, but I suppose this would give me the complete tree when checking out an older revision etc. This might be acceptable, but I would prefer to be able to pretend that the two repositories doesn't have a shared history.  Just to make it clear, I have the following structure:  XYZ/     .git/     XY1/     ABC/     XY2/   But I would like this instead:  XYZ/     .git/     XY1/     XY2/ ABC/     .git/     ABC/ I have seen people showing one slide progressively by pressing Enter. Could anyone tell me how to realize that in Beamer? When is the product of $n$ subgroups a subgroup? Maximum and Minimum values for ints