The book I am looking for was set in the future, overpopulation and poverty were everywhere. A group of homeless/poor kids (maybe young adults) went to a special building where they were placed into simulators several times (i.e., they went back home between each session) where they explored another planet.  At the end of the book, they went there again but soon find out that this time it was the real planet, not just a simulation, and they start rebuilding society.
I'm trying to recall the title of a young adult-targeted book. It was probably published by Scholastic, or at least sold through their take-home pamphlets, which means it was probably published before I started high school in 1996. It's about a group of teenagers who receive invitations to play a game at an invitation-only arcade. When they go there, they are put in an immersive VR game in which they must learn to survive on an alien planet. I believe the game ends and they wake up back in the real world after they fall asleep on the alien one. They are invited back the the game a couple times, and then it turns out…      …they go to play the game again, but they are unable to exit it. Eventually they realize that they actually are on an alien planet now, and that the previous game-playing sessions were just training for the real thing. I believe the epilogue states that all of the players have coupled up and the females have become pregnant, and they are optimistic about populating the new planet.   I think it was told in the first-person perspective of a female player. I don't think there was a real protagonist or strong conflict; just the group of players learning how to survive in the game. One of the other players had a photographic memory and used it to map the planet's surface. I think the cover art featured of a girl wearing a VR headset over her eyes, with her hair being blown back and her mouth open in surprise.
I was wondering how one can construct a Borel set that doesn't have full measure on any interval of the real line but does have positive measure everywhere.   To be precise, if $\mu$ denotes Lebesgue measure, how would one construct a Borel set $A \subset \mathbb{R}$ such that $$0 &lt; \mu(A \cap I) &lt; \mu(I)$$ for every interval $I$ in $\mathbb{R}$?   Moreover, would such a set necessarily have to contain infinite measure? I currently have a Yongnuo YN560-TX trigger and a Yongnuo YN-560 Mark III. I would like to get a iTTL flash that also works with remote triggering.  How compatible are are different flash brands (Neewer, Yongnuo, etc.) when it comes to things like setting zoom, etc. ? How can I build XML in C#? How can I generate valid XML in C#? "sudo -u postgres psql postgres" does not ask for password getting exception while putting list data into the map I can't get grub menu to show up during boot After trying (and failing) to install better ATI drivers in 11.10, I've somehow lost my grub menu at boot time.  The screen does change to the familiar purple colour, but instead of a list of boot options it's just blank solid colour, and then disappears quickly and boots into the default entry normally.    How can I get the bootloader back?  I've tried sudo update-grub and also various different combinations of resolutions and colour depths in startupmanager application with no success (640x480, 1024x768, 1600x1200, 16 bits, 8 bits, 10 second delay, 7 second delay, 2 second delay...)   edit:   I have already tried holding down Shift during bootup and it does not seem to change the behaviour.  I get the message "GRUB Loading" in the terminal, but then the place where the grub menu normally appears I get a solid blank magenta screen for a while.  Here are the contents of /etc/default/grub  # If you change this file, run 'update-grub' afterwards to update # /boot/grub/grub.cfg. # For full documentation of the options in this file, see: #   info -f grub -n 'Simple configuration'  GRUB_DEFAULT=0 GRUB_HIDDEN_TIMEOUT=0 GRUB_HIDDEN_TIMEOUT_QUIET=true GRUB_TIMEOUT=10 GRUB_DISTRIBUTOR=`lsb_release -i -s 2&gt; /dev/null || echo Debian` GRUB_CMDLINE_LINUX_DEFAULT="quiet splash" GRUB_CMDLINE_LINUX=" vga=798 splash"  # Uncomment to enable BadRAM filtering, modify to suit your needs # This works with Linux (no patch required) and with any kernel that obtains # the memory map information from GRUB (GNU Mach, kernel of FreeBSD ...) #GRUB_BADRAM="0x01234567,0xfefefefe,0x89abcdef,0xefefefef"  # Uncomment to disable graphical terminal (grub-pc only) #GRUB_TERMINAL=console  # The resolution used on graphical terminal # note that you can use only modes which your graphic card supports via VBE # you can see them in real GRUB with the command `vbeinfo' #GRUB_GFXMODE=640x480  # Uncomment if you don't want GRUB to pass "root=UUID=xxx" parameter to Linux #GRUB_DISABLE_LINUX_UUID=true  # Uncomment to disable generation of recovery mode menu entries #GRUB_DISABLE_RECOVERY="true"  # Uncomment to get a beep at grub start #GRUB_INIT_TUNE="480 440 1" "There IS/ARE rice, meat and tomatoes on my plate" How do I uninstall the command line tools for Xcode? We have a bunch of Mac at work that no longer require Xcode or command line tools so we'd like to remove them so the compilers aren't hanging around and we don't have to keep updating them when updates arrive. , but now that Xcode is an app store app you are left with the tools if you ever install them. Can we clean this other than wiping the OS for macs running 10.10 and newer? Spaces in files names in \input or \includegraphics Pivot in sql server comment.sty and UTF8 encoding I noted that if I use comment.sty and a there is a block of text containing UTF8 characters inside a comment environment, the compilation aborts!  Minimal Example  \documentclass{article} \usepackage[T1]{fontenc} \RequirePackage[utf8]{inputenc}%this file is stored as UTF8 file! \RequirePackage{comment} \specialcomment{privateSolution}     {\begingroup\itshape\noindent\textbf{Solution}\\}     {\endgroup} %\excludecomment{privateSolution}%Use it to remove solutions!  \begin{document} \title{Comment.sty and UTF8 test file} \maketitle \section{UTF8 character test} In which alphabet characters àìùòè are common? \begin{privateSolution}     The Italian alphabet contains àìùòè. \end{privateSolution}  \begin{comment}     The Italian one! It contains àìùòè. \end{comment} \end{document}   Has anyone the same problem? Any workaround?  Thanks in advance. Invariance of a maximally entangled state under unitary operation $U \otimes U^\dagger$ How does Windows know whether it has internet access or if a Wi-Fi connection requires in-browser authentication? $ not defined using jQuery in WordPress Why didn't Isildur's Heir come forward sooner? Materials for learning TikZ In Quantum Mechanics we usually consider operator-valued functions: these are functions that take in real numbers and gives back operators on the Hilbert space of the quantum system.  There are several examples of these. One of them is when we work with the Heisenberg picture, where we need to consider functions $\alpha : \mathbb{R}\to \mathcal{L}(\mathcal{H})$ such that $\alpha(t)$ is the operator at time $t$.  Another example is when we deal with exponentiation of operators, like when building the time evolution operator:  $$U(t,t_0)=\exp\left(-i\frac{H}{\hbar}(t-t_0)\right),$$  Here, the $\exp$ is usually understood as being defined via the eigenvalues of $H$.  The point is, the idea of a function $\alpha : \mathbb{R}\to \mathcal{L}(\mathcal{H})$ appears quite often in Quantum Mechanics, and sometimes one needs to differentiate these. In practice we do it formally, using all the properties we would expect, but I'm curious about how one would properly define this.  If we were dealing with bounded operators, then we could use the operator norm, which is available for this kind of operator, and define the derivative as we can usually we do when there's some norm around.  The point is that in Quantum Mechanics most of the time operators are unbounded.  So in the general case, how can one define the derivative of one operator-valued function? Calculating the expected values of the min/max of 2 random variables free groups: $F_X\cong F_Y\Rightarrow|X|=|Y|$ I'm reading Grillet's Abstract Algebra. Let $F_X$ denote the free group on the set $X$. I noticed on wiki the claim $$F_X\cong\!\!F_Y\Leftrightarrow|X|=|Y|.$$ How can I prove the right implication (find a bijection $f:X\rightarrow Y$), i.e. that the rank is an invariant of free groups?  I am hoping for a simple and short proof, having all the tools of Grillet at hand. Rotman (Advanced Modern Algebra, p.305) proves it only for $|X|&lt;\infty$, Bogopolski's (Introduction to Group Theory, p.55) proof seems (unnecessarily?) complicated, and Lyndon &amp; Schupp's (Combinatorial Group Theory, p.1) proof I don't yet understand. It's the very first proposition in the book; in the proof, they say:     The subgroup $N$ of $F$ generated by   all squares of elements in $F$ is   normal, and $F/N$ is an elementary   abelian $2$-group of rank $|X|$. (If   $X$ is finite, $|F/N|=2^{|X|}$ finite;   if $|X|$ is infinite, $|F/N|=|X|$). $\square$   Is $N:=\langle w^2;w\in F\rangle$? What is an abelian $2$-group? Elementary? What and how does the above quote really prove? I'm guessing a free abelian group on $X$ is $\langle X|[X,X]\rangle\cong\bigoplus\limits_{x\in X} \mathbb{Z}$?  Can an isomorphism $\varphi:F_X\rightarrow F_Y$ not preserve the length of words? At least one letter words? How do I install nVidia graphics drivers from “X-Swat” ppa? How am I supposed to install nvidia drivers from xorg-edgers? I try  sudo add-apt-repository ppa:xorg-edgers/ppa -y sudo apt-get update sudo apt-get install nvidia-graphics-drivers-331   and I get  E: Unable to locate package nvidia-graphics-drivers-331   The   nvidia-graphics-drivers-331 for trusty, why wouldn't it install?