model technique is very similar to , because both omitting each training case and perform retraining of the network on the left-out subset.  On wiki page we can read that jackknifing computes a statistic from the kept samples only, while LOOCV computes a statistic on the left-out sample(s). However it is still not clear for me.  Can anybody elaborate on it, ideally with same practical examples?
Is there really any difference between the jackknife and leave one out cross validation? The procedure seems identical am I missing something?
How does apt-get really work? Okay, I understand how I may use apt-get {install|upgrade|remove} mypackages to install, upgrade, or remove binaries as well as their configuration data files and dependencies (actually, remove will only remove the binaries unless additional flags are provided).  I am not looking for how it is used as the man describes this, but high level what it is doing.  My end goal is to create a means for me to install and manage some custom software (created by a make file) on multiple remote machines, and I need to learn more about the process.  If answers to this question are based on which distribution is used, please tailor to Debian.  In addition to generally how it works, I have the following specific questions:   How does the client that is accessing the apt repository keep track of the files? Must the repository be hosted on the same operating system (i.e. can apt repository be hosted on redhat)? How are the locations to install files specified?  Is this specified by the .deb file? How is a remote machine accessing the repository?  Is it just ftp(s) or http(s)? Is the machine that is hosting the repository running special software (like gitlab for a git repository), or is it just some structured file system? Earlier I asked a question about  and got the answer that while it is only necessary for anonymous types, that it is used nonetheless to make writing code 'quicker'/easier and 'just because'.  Following  I saw that var gets compiled down to the correct type in the IL (you will see it about midway down article).  My question is how much more, if any, IL code does using the var keyword take, and would it be even close to having a measurable level on the performance of the code if it was used everywhere? How to choose between learning algorithms I need to implement a program that will classify records into 2 categories (true/false) based on some training data, and I was wondering at which algorithm/methodology I should be looking at. There seem to be a lot of them to choose from -- Artificial Neural Network, Genetic Algorithm, Machine Learning, Bayesian Optimization etc. etc., and I wasn't sure where to start. So, my questions is:  How should I choose a learning algorithm I should use for my problem?  If this helps, here is the problem I need to solve.    The training data: The training data consists of many rows like this:    Precursor1, Precursor2, Boolean (true/false)   The run I will be given a bunch of precursors. Then,     I choose an algorithm A from different algorithms (or dynamically generate an algorithm), and apply it on every possible combinations of these precursors and collect the "record"s  that are emitted. The "record" consists of several key-value pairs*. I apply some awesome algorithm and classify these records in to 2 categories (true/false). I will generate a table that has the same format as the train data: Precursor1, Precursor2, Boolean   And the whole program is scored based on how many true/false I got right.  *:"Record"s will look like this (hope this makes sense)  Record         [1...*] Score -Precursor1             -Key -Precursor2             -Value   There are only a finite number of possible Keys. Records contain different subset of these keys (some records have key1, key2, key3... other records have key3, key4... etc.).  I actually need 2 learning. One is for step 1. I need to have a module that looks at the Precursor pairs etc. and decide what algorithm to apply in order to emit a record for the comparison. Another is for step 2. I need a module that analyzes the collection of records and categorize them into the 2 categories (true/false).    Thank you in advance! How to include a PDF image into a PDFLaTeX document Executing multiple commands from a Windows cmd script I'm trying to write a Windows cmd script to perform several tasks in series. However, it always stops after the first command in the script.  The command it stops after is a maven build (not sure if that's relevant).  How do I make it carry on and run each task in turn please?  Installing any software or configuring the registry etc is completely out of the question - it has to work on a vanilla Windows XP installation I'm afraid.  Ideally I'd like the script to abort if any of the commands failed, but that's a "nice to have", not essential.  Thanks. I'm an Indian. I'm planning to book a journey from Mumbai to Johannesburg, South Africa and back (conference visa). I looked at refundable tickets, while they are priced higher, they give you half your money back, for instance if the to and fro flight costs INR 40,000 they give you INR 20,000 . But this is if you are cancelling for some reason.   What if you have to cancel because your visa application or the transit visa application got rejected. As far as I understand the procedure is :-  a. Buy airline tickets   b. Apply for Visa   c. Wait between 1-6 weeks to get update about your visa application, for both visa and transit visa (although transit visa should be shorter I guess.)  d. If visa is granted then move on to planning other things about the trip.   Now in case, if the visa application fails (for whatever reason ) what recourse does the traveler have ?  Are there any airlines who are better understanding than others about this situation ?  In non-refundable tickets, I guess that all is lost or is there some way to save money there too.   Lastly, I read travel insurance can help in this case. How does travel insurance help in the above scenario ?  Edit :- One of the pre-conditions of getting the visa is   Proof of a Valid Return or onward ticket or purchase of ticket. This is from   and I get it after updating in Synaptic Manager  I recently did a clean install of Ubuntu 17.04 from 16.10.  error message:-  W: Download is performed unsandboxed as root as file '/var/cache/apt/archives/partial/samba-libs_2%3a4.5.8+dfsg-0ubuntu0.17.04.1_i386.deb' couldn't be accessed by user '_apt'. - pkgAcquire::Run (13: Permission denied) How to quit Skype on Android? Invalid token 'while' in class, struct, or interface member declaration in very simple code I am not sure what the problem is but I keep receiving this error when I try to use a while statement in my code.     Invalid token 'while' in class,   struct, or interface member   declaration   I want to use a while loop to have something continuously update while a statement is true.  The rest of my code is rather long but whenever I type in the syntax:  while(a&lt;b) { //do whatever i want it to do here }   It gives me that compiler error right off the bat. Not quite sure what the problem is. I am doing this in a C# windows application under the Form1.cs file with all the other event handlers (for buttons and such).  Thanks!    I was unaware that loops had to be placed within a method (fairly new to c#), but I tried it and no errors were returned. Thanks for your help everybody!  Previously, I just had the loop within the main class of the program. Render shadows over a transparent background in cycles I'm trying to make a logo that will be on the header of a website. What I'd like to achieve, and the reason I'm using Blender, is the projected shadows on the background looking perfectly real (as opposed to doing a drop-shadow in Photoshop).  The only thing is, the background has to be transparent because the website might use different background colors / gradients that make it impossible to match with the exported 3D background.  I made this dummy file (not the real logo... duh!):    If I use the file as is, the grey borders of the image will be impossible to match with the website's background color.  Here what I want:    So obviously, I tried masking the plane, which made the shadows disappear. I tried having a plane set to glass, which didn't work either.  And I looked around for a similar question, but didn't find one.   I am not trying to render , or a . I've seen  which has a very difficult solution to this problem, and  that is very similar but in Blender Internal.  is similar too but has never been solved. I'm only a beginner at Compositor, and I'm trying to learn more any chance I get, so any solution in Compositor is welcome if detailed enough. Although if there's a simpler or faster way, it's welcome too!  .blend file: Can you choose which version of a game to play on Steam? What kind of capacitor could build up, and maintain a charge acquired from lightning? Is this proof of $\liminf E_k \subset \limsup E_k $ correct? I am wondering if my proof is correct? Thank you for whoever willing to take a look at it for me.     Proof $\liminf E_k \subset \limsup E_k $   If $\{E_k\}_{k=1}^\infty$ is a sequence of sets, we define \begin{align*} \limsup E_k &amp; = \bigcap_{j=1}^\infty\left(\bigcup_{k=j}^\infty E_k\right)\\ &amp;= \bigcap_{j=1}^\infty(E_j \cup E_{j+1} \cup \cdots)\\ &amp;= (E_1 \cup E_2 \cup \cdots) \cap (E_2 \cup E_3 \cup \cdots) \cap \cdots. \end{align*}  Therefore, $\limsup E_k$ consists of those points in $\mathbb{R}^n$ which belong to infinitely many $E_k$. \begin{align*} \liminf E_k &amp; = \bigcup_{j=1}^\infty\left(\bigcap_{k=j}^\infty E_k\right)\\ &amp;= \bigcup_{j=1}^\infty(E_j \cap E_{j+1} \cap \cdots)\\ &amp;= (E_1 \cap E_2 \cap \cdots) \cup (E_2 \cap E_3 \cap \cdots) \cup \cdots. \end{align*} Therefore, $\liminf E_k$ consists of those points in $\mathbb{R}^n$ which belong to all $E_k$ for $k \geq k_0$.  Now consider $x \in \liminf E_k$, then $x \in E_1 \cap E_2 \cap \cdots$, or $x \in E_2 \cap E_3 \cap \cdots$ and so on, that is to say, $x \in E_{k_0} \cup E_{k_0+1} \cup \dots$ for some $k_0$. More specifically, $x \in E_k \forall k \geq k_0$. Therefore, $x \in (E_1 \cup E_2 \cup \cdots) \cap (E_2 \cup E_3 \cup \cdots) \cap \cdots$, so we showed $x \in \limsup E_k$. How can I undo git reset --hard HEAD~1? Is it possible to undo the changes caused by the following command? If so, how?  git reset --hard HEAD~1 Different results for integration using Mathematica and MATLAB As a Graduate Mathematics student, my interest lies in Number theory. I am curious to know if Number theory has any connections or applications to physics. I have never even heard of any applications of Number theory to physics. I have heard Applications of linear algebra and analysis to many branches of physics, but not number theory.  Waiting forward in receiving interesting answers! Didn't Harry have any other family he could have searched for? You'd think that as soon as Harry met someone who was friends with his dad, he'd have asked about his family.  Certainly Lupin or Sirius could have told him something of his family, given that they were James' closest friends, and Sirius was "always welcome at the Potters".  Obviously there's nothing in the books, but did J.K. Rowling ever explain why there was no mention of any living relative other than Aunt Petunia, or even what happened to Harry's grandparents? What, exactly, is transferred along supply lines? Supply routes are great when a settlement is just starting out to get things off the ground, but what is specifically transferred along them? I know anything on the  Junk, Aid and Mods tabs are transferred, and Fusion cores and Power Armor pieces aren't. Does that mean weapons, armor and ammo aren't transferred at all?  And what about Food and Water resources? Can I build a farming community with a surplus of food and use that to feed a merchant-only settlement, or are local crops always required? Ditto water. Do elevator upgrades increase your passive credit earnings, too? FaceTime not working on iPhone 6 Plus purchased from Dubai I bought my iPhone 6 Plus in Dubai. I am using the phone in Sri Lanka and I cannot use the FaceTime. How can I use FaceTime while in Sri Lanka?