Steven Landsburg
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 Apr 30 comment Formula for negative polylogarithms Does this help? landsburg.com/query.pdf Apr 26 awarded Custodian Apr 25 comment Encoding vectors of size $n$ in matrices which less than $2n$ rows In view of the OP's evasive responses to further comments on Bob Terrell's answer, I will certainly not be changing my close vote. Apr 25 comment Encoding vectors of size $n$ in matrices which less than $2n$ rows @user90628 : I lost you at "It must be done". Apr 25 comment Encoding vectors of size $n$ in matrices which less than $2n$ rows This appears (from the response to my comment on Bob Terell's answer) to be a homework problem. I am downvoting and voting to close pending a more satisfactory response to that comment. Apr 25 comment Encoding vectors of size $n$ in matrices which less than $2n$ rows @user90628 : i don't understand this at all. What defines the problem? Why don't you want to change the way the product is computed? Apr 25 comment Encoding vectors of size $n$ in matrices which less than $2n$ rows @user90628 : Why can't you use the max operator? Apr 16 comment Generalization of the fiber changing trick for principal bundles? Locally, $E\approx B\times G$ so locally $E\times_GF\approx B\times (G\times_G F)$ . Apr 16 awarded Good Answer Apr 3 awarded Good Answer Apr 1 awarded Nice Answer Apr 1 comment Examples of math hoaxes/interesting jokes published on April Fool's day? @quid (and KConrad): My apologies. I'd quite overlooked the comment. Apr 1 answered Examples of math hoaxes/interesting jokes published on April Fool's day? Mar 9 comment Are submodules of free modules free? Onay oremay ommentscay, easeplay. Feb 17 comment Rings such that all quotients by prime ideals are PIDs? @quid: Thanks! $\phantom{xxxxxxxxxxxxxx}$ Feb 17 comment Rings such that all quotients by prime ideals are PIDs? What does one-and-a-half generated mean? Feb 16 revised Source and context of $\frac{22}{7} - \pi = \int_0^1 (x-x^2)^4 dx/(1+x^2)$? Changed $-1$ to $-2$. (I.e. corrected minor typo) Feb 12 comment if 0→A→A⊕B→B→0 is an exact sequence of finitely generated modules over a commutative Noetherian ring, then the exact sequence does split See my answer here: mathoverflow.net/questions/167701/… Feb 8 comment Grothendieck, A Place to Begin I mostly agree with Joe Silverman. You certainly need some commutative algebra first. But I'd start with Mumford's red book rather than Hartshorne. The first part is a very clear presentation of a (somewhat) more classical approach so you understand what schemes are intended to generalize, and the second part is a very clear presentation of scheme theory with emphasis on why it's the right generalization. There's no cohomology, but first things should come first. Jan 28 comment If $A$ is the ring of continuous functions on a genus $g$ surface, can the genus of $X$ be seen by simple algebra in $A$? Given the ring $A$, one recovers the space $X$ as the MaxSpec of $A$, and then you can compute the genus (or any other topological invariant) of $X$ any way you like --- for example, via Cech cohomology. The two steps --- going from $A$ to $X$ and going from $X$ to its genus --- are easily described, so it's easy to describe the composition. "Easily described" is not the same thing as "transparent", but I don't see a reason to expect transparency.