A way to accept more than one answer would be useful More often than not, I get more than one really good answer to a particular question that I have posted.  There is no way one can appreciate that more than by up-voting both answers, because we are only allowed to accept one answer, and I have already accepted another answer.     A way to accept more than one answer would be useful.
Accept Multiple Answers or Split Bounty among Several Users Often more than one person contributes to the community coming up with the final accepted answer to a question. However, it is only possible to accept a single answer. Restricting to one final answer does make sense for the sake of referencing that answer later, but in many cases that answer is the product of the input from several individuals. I would like to be able to decide how much of a bounty goes to different users, or some other mechanism to recognize the contribution of multiple users. Of course I could always upvote their previous answers, but this is really incorrect if their previous answers aren't the complete, final answer I've accepted.  What think you metaSOrs?
What is the formula for this numerical series? Do community and moderator deletes penalize in the same way that self-deletes do? Can I store the .git folder outside the files I want tracked? I have an unusual idea to use git as a backup system. So let's say I have a directory ./backup/myfiles and I want to back that up using git. To keep things clean I don't want to have a .git directory in the myfiles folder, so I thought I could create ./backup/git_repos/myfiles. From looking at the git docs, I've tried doing this:  $ cd backup/myfiles $ mkdir ../git_repos/myfiles $ git --git-dir=../git_repos/myfiles init Initialized empty Git repository in backup/git_repos/myfiles/ $ git --git-dir="../git_repos/myfiles/" add foo fatal: pathspec 'foo' did not match any files   You can see the error message I get there. What am I doing wrong? Lenovo Legion Y720 laptop Keyboard backlight I just moved from Windows to Ubuntu, but I cannot get the keyboard backlight to work at all. On Windows there was a specific program for controlling the backlight. I have searched for days now without luck. Anyone got a solution?  I am using Ubuntu 18.04 Proving that two systems of linear equations are equivalent if they have the same solutions I've just begun to work learn Linear Algebra on my own through Hoffman and Kunze's book and the first problem set already has a question that I can't solve:  Prove that if two homogeneous systems of linear equations in two unknowns have the same solutions, then they are equivalent.  I can't seem to figure out how to prove this without resorting to case work where you account for the cases where one of the coefficients are zero and when both are.  Is there an elegant way to prove in general that when two systems of linear equations have the same solutions, they are equivalent? The converse is obvious enough though.  Definition of equivalence from the text :     Let us say that two systems of linear equations are equivalent if each equation in each system is a linear combination of the equations   in the other system. Style/class tutorials What are some good tutorials on writing custom styles (classes) that clearly explain commands used and some of the features that TeX has to offer in the way of styles? I'm not sure how password hashing works (will be implementing it later), but need to create database schema now.  I'm thinking of limiting passwords to 4-20 characters, but as I understand after encrypting hash string will be of different length.  So, how to store these passwords in the database? Why do I get the error "failed unmounting /var" during shutdown? I have a fresh install of Debian 9.0.0. It has a separate 1 GB partition for /var formatted at ext4. When I shutdown from the terminal, using shutdown -h now, there is a bright-red error message stating "failed unmounting /var".  What is the fix for this error? Can you grab the blue shirts and socks?   Is the above sentence stating that both the shirts and the socks are blue? Or only the shirts?  At this stage, I am leaning towards the earlier (only the shirts) — though writing "Can you grab the blue shirts and blue socks?" seems redundant. I have a Python regular expression that contains a group which can occur zero or many times - but when I retrieve the list of groups afterwards, only the last one is present. Example:  re.search("(\w)*", "abcdefg").groups()  this returns the list ('g',)  I need it to return ('a','b','c','d','e','f','g',)  Is that possible? How can I do it? Set origin to bottom center of multiple objects I have a lot of 3D objects of various sizes, shapes in blender 2.76b and I would like to set the origin to the bottom center of the objects bounds.  I cannot select the bottom edge and snap to cursor etc as each shapes edges are in different X/Y positions.  Is there a script or tool that will allow me to set the origin to the lowest edge z position? Show default image when no uploaded image XGBoost Loss function Approximation With Taylor Expansion As an example, take the objective function of the XGBoost model on the $t$'th iteration:  $$\mathcal{L}^{(t)}=\sum_{i=1}^n\ell(y_i,\hat{y}_i^{(t-1)}+f_t(\mathbf{x}_i))+\Omega(f_t)$$  where $\ell$ is the loss function, $f_t$ is the $t$'th tree output and $\Omega$ is the regularization. One of the (many) key steps for fast calculation is the approximation:  $$\mathcal{L}^{(t)}\approx \sum_{i=1}^n\ell(y_i,\hat{y}_i^{(t-1)})+g_tf_t(\mathbf{x}_i)+\frac{1}{2}h_if_t^2(\mathbf{x}_i)+\Omega(f_t),$$  where $g_i$ and $h_i$ are the first and second derivatives of the loss function.   What I'm asking for is convincing arguments to demystify why the above approximation works:  1) How does XGBoost with the above approximation compare to XGBoost with the full objective function? What potentially interesting, higher-order behavior is lost in the approximation?  2) It's a bit hard to visualize (and depends on the loss function) but, if the loss function has a large cubic component, then the approximation will likely fail. How is it that this doesn't cause problems for XGBoost? UILabel truncate tail and skip not complete word How do I get lightning:datatable to do some undocumented thing X? What is the difference between $* and $@? I understand that a black hole bends the fabric of space time to a point that no object can escape.   I understand that light travels in a straight line along spacetime unless distorted by gravity. If spacetime is being curved by gravity then light should follow that bend in spacetime.  In Newton's Law of Universal Gravitation, the mass of both objects must be entered, but photon has no mass, why should a massless photon  be affected by gravity in by Newton's equations?  What am I missing? Are there any options of bash with which it is invoked? I  that the default shell that I use when I start Terminal (with Ctrl+Alt+T) is /bin/bash.   And running the built-in command  on  as:   type -p bash   returns the result as:  /bin/bash   Suggesting the same executable is run when I do Ctrl+Alt+T or say bash.  This shell is the same as an invocation of the command  with some of its options passed to it right? If yes, what are these options?   As an example, perhaps the -i option gets passed so as to make the bash shell interactive?   PS: Maybe  is related too, but I cannot seem to piece together all the pieces here. Which profile details does an account merge preserve? When one has to merge two accounts, they're prompted by something like this with input fields for each account link:     Account 1:  Account 1 link.       Account 2:  Account 2 link.    When the merge completes, which account details are preserved, like the display name, or the profile description? Account 1, or account 2? allow you to create code which defines the methods of classes that implement it. You cannot however add any code to those methods.    allow you to do the same thing, along with adding code to the method.   Now if you can achieve the same goal with abstract classes, why do we even need the concept of interfaces?   I've been told that it has to do with OO theory from C++ to Java, which is what PHP's OO stuff is based on. Is the concept useful in Java but not in PHP? Is it just a way to keep from having placeholders littered in the abstract class? Am I missing something?