In boosting, if the base learner is a linear model, does the final model is just a simple linear model?
Gradient Boosting for Linear Regression - why does it not work?
Any way to embed Pygame in webpages? Can you filter out certain SE sites from the hot questions list? Is it possible to filter out Stack Exchange sites from the hot questions list? I dont have a clue about the proof in the reverse implication on the iff statement.  I will show what I have by now:  1) A cofinite topology implies that any infinite subset in $X$ is dense. Let $U\in\tau$ and is cofinite topology so $U=X-\bigcup_{k=1}^{n}\{x_k\}$.  Let $V\in X$ an infinite subset then $$V\cap U=V\cap(X-\bigcup_{k=1}^{n}\{x_k\})=(V\cap X)-(V\cap \bigcup_{k=1}^{n}\{x_k\})=V-(V\cap \bigcup_{k=1}^{n}\{x_k\})$$  and cause $|V|\ge\aleph_0$ and $|\bigcup_{k=1}^{n}\{x_k\}|=n\in\Bbb N\,$ we have that $|V\cap \bigcup_{k=1}^{n}\{x_k\}|\le n$. And finally is obvious that $V-(V\cap \bigcup_{k=1}^{n}\{x_k\})\ne\emptyset$ so any infinite subset is dense on $X$.  2) A cofinite topology implies a $T_1$-space. Let $x, y\in X$ and $U\in\tau: U=X-\{y\}$ so $x\in U\land y\notin U$. We can define too $V\in\tau:V=X-\{x\}$ so $x\notin V\land y\in V$ then a cofinite topology is a $T_1$-space.  But my problem is that I dont have a clue to prove the reverse implication i.e. if we have a $T_1$-space where every infinite subset is dense then it is a cofinite topology. Some hint? Some advice or correction in the proof of above? Thank you in advance.    I will complete the proof with the advice of @Cameron Buie.  1) A $T_1$-space implies that any finite subset is closed. Let the singleton $\{x\}\subset X$. Then $\overline{\{x\}}=\{x\}\cup\{x\}'$ where $\{x\}'=\{y:(\forall U\in\tau : y\in U)\land x\in U\}$, but because we are in a $T_1$-space exist some $U$ for any points $x,y\in X: x\in U\land y\notin U$ so $\{x\}'=\emptyset$ then $\overline{\{x\}}=\{x\}$ and is closed.  This means that for every $T_1$-space it cofinite sets are open.  2) If any infinite subset is dense on $X$ it means that the closure of any infinite subset is $X$ so the only closed sets are finite (and $X$ itself), so the topology is cofinite. Let $p&gt;3$ be a prime. Prove that $24 \mid p^2-1$.   I know this is very basic and old hat to many, but I love this question and I am interested in seeing whether there are any proofs beyond the two I already know. Database does not update automatically with MySQL and Python I'm having some trouble updating a row in a MySQL database. Here is the code I'm trying to run:  import MySQLdb  conn=MySQLdb.connect(host="localhost", user="root", passwd="pass", db="dbname") cursor=conn.cursor()  cursor.execute("UPDATE compinfo SET Co_num=4 WHERE ID=100") cursor.execute("SELECT Co_num FROM compinfo WHERE ID=100") results = cursor.fetchall()  for row in results:     print row[0]  print "Number of rows updated: %d" % cursor.rowcount  cursor.close() conn.close()   The output I get when I run this program is:     4Number of rows updated: 1   It seems like it's working but if I query the database from the MySQL command line interface (CLI) I find that it was not updated at all. However, if from the CLI I enter UPDATE compinfo SET Co_num=4 WHERE ID=100; the database is updated as expected.  What is my problem? I'm running Python 2.5.2 with MySQL 5.1.30 on a Windows box. Does anyone know how to get your business map location displayed in the right hand sidebar of the Google search results page? As in the screenshot below:      I already added my business to this link: .  Is adding detail in above link enough or do I need to change my website coding? Compare two files with first column and remove duplicate row from 2nd file in shell script I will ask my question with an example. I have 2 files:  File #1:  118D FC300_R5_TP  FX.B      32775       2112   6       2038   6       2112   0 118E FC300_R5_TP  FX.B      32775       2136   7       2065   6       2136   0 118F FC300_R5_TP  FX.B      32775       2124   6       2064   6       2124   0 1190 FC300_R5_TP  FX.B     819210     814632  99     814609  99     814632   0 1191 FC300_R5_TP  FX.B     819210     104100  13     103714  13     104100   0 1192 FC300_R5_TP  FX.B    1638420    1609476  98    1609402  98    1609476   0 1196 FC300_R5_TP  FX.B    1638420    1638432 100    1638379 100    1638432   0 119A FC300_R5_TP  FX.B    3276840    3271776 100    3271698 100    3271776   0 119E FC300_R5_TP  FX.B    3276840    3264120 100    3264034 100    3264120   0 11A2 FC300_R5_TP  FX.B    3276840    2328648  71    2328546  71    2328648   0 11A6 FC300_R5_TP  FX.B    3276840    2328444  71    2328355  71    2328444   0 11AA FC300_R5_TP  FX.B    3276840    2328528  71    2328403  71    2328528   0 11AE FC300_R5_TP  FX.B    3276840    2328648  71    2328468  71    2328648   0 11B2 FC300_R5_TP  FX.B    3276840    2130000  65    2129766  65    2130000   0 173A FC300_R5_TP  FX.B    6553680    6478572  99    6477747  99    6478572   0   File #2:  11AA FC300_R5_TP  FX.B    3276840    2328528  71    2328403  71    2328528   0 11AE FC300_R5_TP  FX.B    3276840    2328648  71    2328468  71    2328648   0 11B2 FC300_R5_TP  FX.B    3276840    2130000  65    2129766  65    2130000   0 173A FC300_R5_TP  FX.B    6553680    6478572  99    6477747  99    6478572   0 0BDB FC600_R5_TP  FX.B   33554640    6044364  18    6033105  18    6044364   0 0BDC FC600_R5_TP  FX.B   33554640    6613536  20    6481974  19    6613536   0 0BDD FC600_R5_TP  FX.B   33554640    4435848  13    4057170  12    4435848   0 0BDE FC600_R5_TP  FX.B   33554640    6620868  20    6249518  19    6620868   0   Desired Output  File #3:  0BDB FC600_R5_TP  FX.B   33554640    6044364  18    6033105  18    6044364   0 0BDC FC600_R5_TP  FX.B   33554640    6613536  20    6481974  19    6613536   0 0BDD FC600_R5_TP  FX.B   33554640    4435848  13    4057170  12    4435848   0 0BDE FC600_R5_TP  FX.B   33554640    6620868  20    6249518  19    6620868   0   I'd like to compare file 1 and file 2 using their first columns and remove the entire line or row from file 2 where they match in file 1. I'd also like to save the results to a 3rd file, file #3. Proof that every repeating decimal is rational I'm really new in using biblatex, compile the sample placed in , but what I get is    1.1 Foo    Some text [B02x ].    1.2 Bar    Some text [B02y ].   Do not get the bibliography by chapters, or the global references.  Really not remains to be done   \documentclass{report}  \usepackage[style=alphabetic]{biblatex}  \addbibresource{references.bib}  \begin{document}  \chapter{First chapter}  \section{Foo}  Some text \cite{childs_temperature}.  \printbibliography  \chapter{Second chapter}  \section{Bar}  Some text \cite{hashemian}.  \printbibliography  \newpage  \printbibliography  \end{document}   And the references.bib    @BOOK{childs_temperature,   title = {Practical Temperature Measurement},   publisher = {Butterworth - Heinemann},   year = {2001},   author = {Childs, Peter R N},   address = {Great Britain},   edition = {1},   isbn = {0 7506 5080 X}   }    @PHDTHESIS{hashemian,   author = {Hashemian, Hashem Mehrdad},   title = {Measurements of dynamic temperatures and pressures in nuclear power plants},   school = {{The University of Western Ontario}},   year = {2011},   type = {PhD {T}hesis}   }   I need to obtain references by chapter and global cited references, but i don't know how compile. Cleaning polygon after using dissolve to repair geometry in QGIS? I'm trying to obtain the boundaries of shapefile, thus to clean the inside as a matter of speaking. While I had expected that dissolve while get me a proper polygon, unfortunately it still has some remainders. How could I get rid of them?  Does QGIS have a tool similar to Repair Geometry?  Here's the source    Result below: Why are my photos not crisp? I've used "//" and "\" to create this "W", and have made them into outlines, as I'm trying to give the different layers a colour, as well as having a white space where the lines touch and I would like to remove the top of the second "\".   I'm struggling with the white space at the moment and now I've added a stroke, the fill has decreased. Is there another way I could do this?   I've also tried to use my pen tool to remove the top of the "\" but when using "Path Finder" I cannot find an option to "Minus Forward". I'm a newbie so any advice would be lovely :) How to prove positive semidefiniteness of two matrices through Schur Complement? Let matrices $X$ and $Y$ be positive semideﬁnite. Show that $X \succeq Y \succ 0$ is equivalent to $Y^{-1} \succeq X^{-1}$.   The teacher tells me that it is easy to prove via the Schur complement. But I could not get his idea. Could anyone help me and give me some intructions? Thanks in advance! Did this character lose a limb in “The Force Awakens?” Inspired by  which states limb loss as a recurring theme, I started thinking about the final lightsaber battle. After watching The Force Awakens the second time, I was not sure if      Kylo Ren   lost a limb or just lost his lightsaber. We definitely see      Rey slash at Ren’s right hand.   So knowing that context:      Did Kylo Ren actually lose his arm/hand? How to start a GUI application from cron? Root drive is running out of disk space. How can I free up space? Is there a 2D generalization of the coefficient of restitution? The  characterizes a collision in one dimension by relating the initial and final speeds of the particles involved,  $$C_R = -\frac{v_{2f} - v_{1f}}{v_{2i} - v_{1i}}$$   In a 2D collision, the velocity can be split into components parallel and perpendicular to the "plane of collision" (the plane tangent to the two objects' surfaces at their contact point), and the equation above applies to the perpendicular components of the velocities only. One could write  $$\begin{pmatrix}v_{2f\shortparallel} - v_{1f\shortparallel} \\ v_{2f\perp} - v_{1f\perp}\end{pmatrix} = \begin{pmatrix}1 &amp; 0 \\ 0 &amp; -C_R\end{pmatrix}\begin{pmatrix}v_{2i\shortparallel} - v_{1i\shortparallel} \\ v_{2i\perp} - v_{1i\perp}\end{pmatrix}$$   My question is, is it useful (i.e. does it produce a more accurate description of realistic 2D collisions) to generalize that matrix? Perhaps by allowing the top left element to be unequal to 1, or allowing nonzero off-diagonal elements? Or is there some nonlinear relation that works better?  As usual, if you know of any relevant published research, references would be much appreciated. Contraction mapping in the context of $f(x_n)=x_{n+1}$. We have various ways of invoking apex. Triggers, Inbound Webservices, @InvocableMethod,@RemoteAction and what not. Often we call some or other utility methods from these execution contexts. I have some generic utility method,that should behave differently from the context it is called?  I know about Trigger.isExecuting but it only tells if its running in trigger context or not.  I have a utility method that creates lead from Webservices, VF button click and via Lightning . Whenever we create a lead I want some special operations to be done via the source it was originated.(Its not just updating a simple field leadSource, I have some methods that creates some childs and update other records of other type) . I can achieve this by passing an extra parameter to utility method to tell about source, but i have then to edit hundred of other class that uses this utility method. If i could dynamically find out via which context this piece of code is running,then i would have to change only one class to satisfy my requirement.    Is there something in APEX that tells in what context the apex method was called? How do i fix this Eevee rendering Problem? I can notfix this issue when selecting Eevee for my renders. It gets really annoying. I can get rid of them temporary when I scroll out or into the viewport. Does anyone have an Idea how I can fix that?  thanks c: