Bart Patzer
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 Dec7 awarded Popular Question Dec2 awarded Yearling Jul2 awarded Curious Oct5 accepted How to iterate over power set in MAGMA? Oct5 revised How to iterate over power set in MAGMA? added 141 characters in body Oct5 asked How to iterate over power set in MAGMA? Sep11 accepted Picking out columns from a matrix using MAGMA Sep9 asked Picking out columns from a matrix using MAGMA May23 revised Extending an ideal of a polynomial ring to a polynomial ring with more indeterminates. Is it a tensor product? deleted 85 characters in body May16 accepted Is the image of a tensor product equal to the tensor product of the images? May16 comment Is the image of a tensor product equal to the tensor product of the images? Thanks a lot for great answer. I don't quite see what the unique injection $\mathbb{Z}/2\mathbb{Z}\rightarrow\mathbb{Q}/\mathbb{Z}$ is though...could you please tell me? And what if all the modules $A,A',B,B'$ are free $S$- modules (even finitely generated), do we then have $$\operatorname{im}(\phi\otimes\psi)=\operatorname{im}(\phi)\otimes_{S}\operator‌​name{im}(\psi)?$$ May16 asked Is the image of a tensor product equal to the tensor product of the images? May5 comment Showing that the Taylor series of $f(x)=\frac{1}{\sqrt{1+x}}$ converges to $f$ on (I think) the interval (-1,1]. Well, thanks a lot. This is a first year calculus exercise though, and neither complex analysis nor binomial coefficients involving non-natural numbers are part of the curriculum...far from it:) May5 asked Showing that the Taylor series of $f(x)=\frac{1}{\sqrt{1+x}}$ converges to $f$ on (I think) the interval (-1,1]. May5 accepted Manipulation of some power series (probably integration or derivation). May4 comment Manipulation of some power series (probably integration or derivation). Well, but using the series for $ln(1+x)$ and $ln(1-x)$ together with $\ln(a/b)=\ln(a)-\ln(b)$, which I had already tried, doesn't yield the deisred identity. I am pretty sure one is supposed to use the sum for $\frac{1}{1-x^2}$ mentioned above. And the absolute values, pointless though they are, I think may be a hint that one is supposed to integrate both sides of something, since \integral 1/y = ln|y| + C. But I still have no idea how to solve this exercise. May4 asked What happens to the sequence $a_n=\frac{3\cdot5\cdot7\cdot\ldots\cdot(2n-1)}{2\cdot4\cdot6\cdot\ldots\cdot2n}$ as $n$ tends to $\infty$? May3 asked Manipulation of some power series (probably integration or derivation). Apr28 awarded Commentator Apr28 comment When is every spanning tree of a connected graph the union of spanning trees of its subgraphs? In general, if the proposition holds for some $\{H_i\}$, then it holds for any "coarser partition" of $\{H_i\}$ as well.