Children's Sci-Fi novel 1980s, another planet with moth-like creatures and glass-like grass I'm trying to figure out the title of a book I read as a child -- probably around 1988 -- aimed at 9-10 year olds.  The story had to do with people leaving Earth and they were only able to take one personal item with them each.  I remember one person bringing a biology book -- which was helpful.  When they arrived at the new planet, there was glass-like grass that burned funny colors and strange stones around that turned out to be eggs for some beautiful moth-like creatures.  If it helps, this was a reading assignment given to me in the 5th grade in the United States.  Any ideas on what book this might have been?
Story Identification: colonists on a planet where the wheat is crystalline I read a story back in the early 90s about a group of colonists who landed on a planet where the wheat (or wheat-like equivalent) is some kind of crystalline plant. The colonists face starvation until one of them figures out how to process the wheat.  I think it was by Asimov but so far I haven't found it by looking for his works.  I also cannot remember if it was a novel or a short story.
How to prove $( A \times B ) \cap ( C \times D ) = ( A \cap C ) \times ( B \cap D )$ ? Now that experience does something besides render regions of a server uninhabitable due to  orb lag, what's the most efficient and safe way to get those excellent enchants?  A mob farmer may rank highly, but what about without tons of setup? Port error while changing chrome extension from manifest v1 to v2 Prove that you can make change for any amount greater than 7 cents using only 3 and 5 cent coins. I am pretty sure this question has something to do with the Least Common Multiple.    I was thinking that the proof was that every number either is or isn't a multiple of $3, 5$, and $8\left(3 + 5\right)$. If it isn't a multiple of $3,5$, or $8$, great. You have nothing to prove. But if it is divisible by one of them, I couldn't find a general proof that showed that it wouldn't be divisible by another one. Say $15$, it is divisible by $3$ and $5$, but not $8$. Going to any question on the site brings an error page single word that means which can be constructed at home We have the following points: $$ (0,0)(1,51.8)(1.9,101.3)(2.8,148.4)(3.7,201.5)(4.7,251.1)  \\ (5.6,302.3)(6.6,350.9)(7.5,397.1)(8.5,452.5)(9.3,496.3) $$ How can we find the best fitting line $y=ax$ through the points? My calculator has the option to find the best fitting line $y=ax+b$ through these points, which is:  $$y = 53.28x + 0.37$$  How can I find the best fitting $y=ax$? It seems to me we can't just remove the $0.37$ without compensating in the $a$? Aligning multiple points to line in QGIS? I would like to align multiple points to a line, or lines within a layer, using a specified tolerance or buffer around the line objects. Please refer to the sample sketch attached.  For the sake of this example, the points closest to the line in the BEFORE picture are within 5 map units of the line, while the outermost points are over 10 map units away. I would like to snap the closest points onto the nearest line, using a tolerance of 5 map units to achieve the result in the AFTER picture. Could anyone give me an explanation of the meaning of "get one's finger in the air" and the usage of it? ImageView without xml definition I've completed my contracts. Now what? I completed the two contracts I was given (Scout and Heavy), and earned two of the 'Teufort' weapons for turning them in.  I expected to get some new contracts so I could continue to earn some more of the schmancy new weapons, but I can't seem to find out how to get more.  Do I need to buy the ticket again to unlock more contracts? If not, how are contracts assigned? How do I fix the GPG error "NO_PUBKEY"? I added some extra repositories with the Software Sources program. But when I reload the package database, I get an error like the following:     W: GPG error:  trusty InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 8BAF9A6F   I know I can fix it using apt-key in a terminal, according to the official Ubuntu documentation. But I would have liked to do it graphically. Is there a way to do this without using a terminal? Converting truth tables to boolean expressions I'm using a custom class file.  My main file looks like this:  \documentclass[12pt,a4paper]{thesis} \begin{document} \frontmatter     \pagenumbering{alph}      \pagenumbering{roman}     \clearpage      \cleardoublepage     \tableofcontents     \clearpage     \listoffigures     \clearpage     \listoftables   \mainmatter        \part{test}       \input{test} \end{document}   If I put this in my test.tex it does work:  \chapter{test} \label{chapter:test} test    When it becomes more text (lets say 40x the word "test") I get the error stated in my question title.  To test it I brought my class file down to this:  \ProvidesClass{thesis} \NeedsTeXFormat{LaTeX2e}  % Based on the memoir class \DeclareOption*{\PassOptionsToClass{\CurrentOption}{memoir}} \ProcessOptions \LoadClass{memoir}   I'm totally confused what is causing my error now.  This is the complete error:  ! pdfTeX error (font expansion): auto expansion is only possible with scalable  fonts. \AtBegShi@Output ...ipout \box \AtBeginShipoutBox                                                    \fi \fi $x^3+x+1$ irreducible over $\mathbb{F}_2$, $\theta$ root, compute powers of $\theta$ Problem statement:     Show that $x^3+x+1$ is irreducible over $\mathbb{F}_2$ and let $\theta$ be a root. Compute the powers of $\theta$ in $\mathbb{F}_2$.   I am having trouble computing the powers of $\theta$. $x^3+x+1$ is irreducible, since any cubic polynomial over a field is reducible if and only if it has a root in the field. Since $\mathbb{F}_2=\{0,1\}$, we see that none of these is a root of $x^3+x+1$.  To compute the powers of $\theta$, note that $\theta^3+\theta+1=0$. Hence $\theta^3=-(\theta+1)$. Is this a good enough answer for $\theta^3$?  To compute $\theta^2$, note that $\theta = -(\theta^3+1)$. Therefore, $$\theta^2=(\theta^3+1)^2 = \theta^6 + 2\theta^3 + 1 = (-\theta-1)^2-2\theta-2+1,$$ which just reduces to $\theta^2$. Any ideas for computing these powers?  Thanks! Is a clean install better than upgrading? How does the Doctor know how old he is? I've often wondered, how does the Doctor know how old he is? He not only travels through time, but also through space, and visits planets where days can be shorter or longer than 24 hours. How does he 'keep score'?  Also, does he count his age in Earth years or Gallifrey years? They might be completely different in length. Did Dolores Umbridge Have Any Association with Voldemort (or Death Eaters) before His Return? Where did the disco repos go, or what is going on? Currently, the only way to vote to delete (and undelete, since you can't see deleted posts) in the Android app is to open the post in a browser, and then vote to delete from there.  Can we get delete vote functionality within the app, as well as the ability to delete our own posts?  Worth to mention: users , so it's possible in the API.  Related: