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Pierre-Yves Gaillard's user avatar
Pierre-Yves Gaillard's user avatar
Pierre-Yves Gaillard's user avatar
Pierre-Yves Gaillard
  • Member for 15 years, 2 months
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Classify commutative rings $R$ such that $A \otimes_{\Bbb Z} B = A \otimes _{R} B$
Not sure it helps but (if I'm not mistaken) the condition is clearly equivalent to $\text{Hom}_R(A,B)=\text{Hom}_{\mathbb Z}(A,B)$ for all $R$-modules $A$ and $B$.
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Noetherian spectral space comes from noetherian ring?
@KarlSchwede - You may want to take look at my comment below.
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Noetherian spectral space comes from noetherian ring?
See also top of p. 48 in Ring constructions on spectral spaces by Christopher Francis Tedd escholar.manchester.ac.uk/jrul/item/?pid=uk-ac-man-scw:30701‌​2 --- link to the PDF file: escholar.manchester.ac.uk/api/…
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Rings in which every non-unit is a zero divisor
See Atiyah & MacDonald, Exercise 3.9, parts (ii) and (iii), p. 44.
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Is $\mathrm{Hom}(P^i,P^j)$ a finite set? ($P=$ power set functor, $i\equiv j\bmod2$)
changed \text to \mathrm as suggested by David Roberts
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Is $K[[x_1,x_2,\dots]]$ an $\mathfrak m$-adically complete ring?
Thanks a lot!!! Sadly I don't know enough algebraic geometry to fully understand your answer. But I'll still ask you an elementary question. It seems to me you could set $r_n:=n$ throughout, because when you prove the lemma, you start with arbitrary $n$ and $r$. Am I right?
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Is $K[[x_1,x_2,\dots]]$ an $\mathfrak m$-adically complete ring?
@EhudMeir - Thanks! You posted your second comment while I was writing the following answer to your first comment. In the definition of $A=K[[x_1,x_2,\dots]]$ that I gave (and which I found in Bourbaki), the notation $\sum_ua_uu$ is completely formal. In other words, this formal sum represents an element of $A$, but not the sum of a series. To say it in yet another way, $A$ is not defined as the $(x_1,x_2,\dots)$-adic completion of $K[x_1,x_2,\dots]$.
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What books should I read before beginning Masaki Kashiwara and Pierre Schapira's "Sheaves on Manifolds"
I hope the title and the posts will be edited, but the current title and the current post mention "Masaki Kashiwara's book Sheaves on Manifolds", although the book has two authors, Masaki Kashiwara and Pierre Schapira.
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Is every odd positive integer of the form $P_{n+m}-P_n-P_m$?
@ĐàoThanhOai - The usual terminology is to call elements of $\mathbb Z$ integers, and to say that an integer $n\in\mathbb Z$ is nonnegative if $n\ge0$ and positive if $n>0$. Also, if you want a user to be notified, you can use the @ symbol.
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Is every odd positive integer of the form $P_{n+m}-P_n-P_m$?
By "integer", do you mean "positive integer", or do you really mean integer?
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