LaTeX and Plain TeX are formats for TeX and they ease creating document. But can we create documents using only TeX? I couldn't find any pure TeX sample.
all the LaTeX-tutorials tell me how LaTeX is an extention simplifying the building of TeX documents. Understandably, no one uses plain TeX anymore, right?  But I seem to learn better when I grasp the link between TeX and LaTeX. Does someone have a link to example files in plain TeX? I'd like to know which commands, macros etc. are LaTeX-specific.
Is it wrong to place the  tag after the  tag? Why doesn't Neo teleport at random? Alternate moves, first one to roll a 6 wins: what's the probability of winning? Question: Players A and B play a sequence of independent games. Player A starts and throws a fair die and wins on a "six". If she fails then player B throws the same die and wins on a "six" or fails otherwise. If she fails then player A gets the die and throws again, and so on. The first player to throw a "six" wins. Find the probability that player A wins.  Here is what I have done:  A wins right away: $\dfrac{1}{6}$  A fails B wins: $\dfrac{5}{6}\times \dfrac{1}{6}$  A fails B fails A wins: $\dfrac{5}{6}\times \dfrac{5}{6}\times \dfrac{1}{6}$  Unlike another similar question which the player B can win on "five" and "six" after player A fails on the first throw, in this case, the games do not seem to have an endpoint. How should I calculate the probability that player A wins then? How can I sanitize user input with PHP? When editor does not respond to the request for withdrawal I submitted a manuscript to a journal, but due to some issue with that I asked the Editor-in-Chief and Associate Editor to withdraw the manuscript from further consideration. Despite several emails, they are not still responding me nor ended the process.  Now, what should I do? Can I submit the manuscript to another journal? Why doesn't the Related question list show that questions are closed? I saw a question on Meta that was obviously going to be a duplicate:        And indeed, looking at the "Related" questions list for that question showed a number of duplicates:    Being the good citizen I am, I tried to vote to close (technically Flag as duplicate as I've not got the rep here to vote to close) it as an Exact Duplicate only to find myself falling into a rabbit hole of Closed, Duplicate questions. Is there any way to flag a closed question as such in the Related list?  Mostly because the first one I picked was closed as a duplicate of the second one, which was closed as a duplicate of the one that is now listed as the duplicate/linked answer.   Edit to respond to comment:  I take the point about "not voting to close on title alone", and normally wouldn't, however as the questions had identical titles, and it's pretty clear what they should be asking, I clicked the first one:    which lead to:  which leads to:  - but I'd got bored following links and didn't check that one as the first two were identical, so assumed this was too and didn't want to see how deep the rabbit hole led.   In the related list, there's only one other question in there that is an exact duplicate, but hasn't (currently) been closed as such which is:      Reasoning for highlighting closed questions:  The "Questions with similar titles" does display the closed titles when asking the question, so it should be fairly possible to include.  If there are clearly duplicate titles, then as a reader/reviewer would be helpful to know which ones are already closed as duplicates so you can either:   Use the remaining open questions to focus on which of those is the canonical answer to close this with. Use the closed questions to find the canonical answer (which failed for me with my route of clicks). Homomorphism between free groups Let $F_a$ be the group which is freely generated by $a$ elements. How to show that there is a homomorphism from $F_a$ onto $F_b$ if and only if $b\le a$?  I was thinking one possibility is if $F_a$ generated freely by $\{x_1, \dots , x_a\}$ and $F_b$ generated freely by $\{y_1, \dots , y_b\}$ then consider map which says $\phi(x_i)=y_i$ for $1\le i \le b$ and $y_1$ otherwise. I do not know if this works or even how to proceed. How to show this fact? How does ssh run a command? I'm using Bash on both client and server. When running a command over SSH:   ssh &lt;host&gt; 'declare' gives a list of shell variables. ssh &lt;host&gt; 'mount' gives a list of mountpoints.   However, declare is a Bash builtin, while mount is an external command. How does SSH know which to run if there is a shell builtin and an external command with the same name on the server? How to use the keyboard to drag and drop? Last Logon Time of All Users - RDP server not on a domain Here is the problem setup  \begin{equation} \begin{array}{c} \text{min} \hspace{4mm}  \mathbf{b}^{T}_{}\mathbf{A}^{}_{}\mathbf{b}^{}_{} \\ s.t \hspace{5mm} \mathbf{b} \in \mathbb{R}^{N} \\ \hspace{9mm}b_0=1\\ \hspace{62mm}b_i=b_{i-2}b_{i-1} \hspace{5mm} \forall \hspace{5mm} 2&lt;i\leq N-1 \end{array} \end{equation}  where $\mathbf{A}$ is a $N\times N$ positive semi-definite matrix  To handle $b_0=1$ constrain, I know I can introduce Lagrange multiplier in objective function  \begin{equation} \begin{array}{c} \text{min} \hspace{4mm}  \mathbf{b}^{T}_{}\mathbf{A}^{}_{}\mathbf{b}^{}_{} + \lambda(\mathbf{b}^{T}_{}\mathbf{u}^{}_{}-1) \end{array} \end{equation}  where $\mathbf{u}_{}^{}$ is a $N\times 1$ column vector and $u_0=1$ and $u_i=0 \forall 1&lt;i\leq N-1$.  But I dont know how to handle second set of constraints?   EDIT: Example  Let $N=4$. Therefore I am looking for $\mathbf{b}=[b_0 \quad b_1 \quad b_2 \quad b_3]^T = [1 \quad b_1 \quad b_2 \quad b_1b_2]^T$. How do I include $b_3=b_1b_2$ constraint in objective function QGIS area calculation differs when on the fly CRS transformation enabled When I open QGIS, add the layer, and calculate the areas of the shapefile via field calculator I get a different area than when I open QGIS and check "Enable on the fly CRS transformation" and calculate the area. This is despite making sure that the project and the layer have the same Coordinate system (same EPSG number). What am I doing wrong?   I have a shapefile with area calculations made with ArcGIS (not be me, the data was handed to me and I have no clue for which CRS the area was calculated with ArcGIS). The shapefile layer CRS is EPSG: 21781 (Switzerland). In QGIS, if I do not change the OTF settings and leave the project CRS as EPSG:4326 (WGS84) I get the same value as the ArcGIS area value. However, if I change the OTF before adding the layer to EPSG: 21781 I get different area values. As I understand this suggests that ArcGIS Area was calculated with the CRS EPSG: 4326.  First workflow:   open QGIS  project CRS: EPSG 4326  add layer  project CRS adapts automatically and is EPSG 21781 now  calculate $area with field calculator    Second workflow:   open QGIS  project CRS: EPSG 4326  Turn on OTF, set project CRS to EPSG 21781  add layer  calculate $area with field calculator    Step 5 of the first and second workflow DO NOT produce the same area. In my native language, we can say:     I have dog   Because I don't want to say a dog (one dog, how many dogs) or the dog (that dog, the listener don't care which dog).  p.s. after 3 years later, I have to say, why I ask this question, is I still cannot grasp how to use the right 'article word'. sometimes, a noun will use an article, sometimes, a noun could not(or omit) the article word before it. there aren't a formula for this. So, I have to remember all the time! I feel so frustrate How can I make realistic looking potions as handouts I'd like to give my group some realistic looking potions as handouts.  Does anyone have tips on how I could make these look awesome? Same update keeps showing up everyday What is the expected value of the maximum of 500 IID random variables   with uniform distribution between 0 and 1?   I'm not quite sure of the technique to go about solving something like this. Could anyone point me the right direction?  Thanks How does Annihilation work? CSS background opacity with rgba not working in IE 8 My online friend is asking for money in order to visit my home country. Is this a legit request or a scam? On Travel.SE we often see questions about a person (usually a love interest) asking for money to pay for airfare, visas, permits and other expenses. For example        What general advice can be given in such situations to the person asking the question? Is it all a scam or can there be legitimate situations in which an online friend could be asking for money? Bounded in Probability and smaller order in probability