Bruno Joyal
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 Apr 28 awarded Good Answer Apr 25 comment Expressing Elliptic functions as ratio of $\wp$ and $\wp'$ What is the question? Apr 25 comment Algebraic values of sine function Apr 24 comment If I have matrix A, what is difference between $det(A), det(A_n), det(A_{n+1})$? What are $A_n, A_{n+1}$ and $A_{n+2}$? Without knowing that, your question makes no sense. Apr 22 reviewed Approve Show the series $a_n/(1+a_n)$ converges absolutely Apr 21 revised How do I transpose an ellipse function to stretch the ellipse into curved space? edited tags Apr 20 answered Weirestrass points in Principles of Algebraic Geometry. Apr 19 comment Embedding Complex Tori in Projective Space By an "embedding" in algebraic geometry one often means a closed immersion. Apr 19 comment Determine $H(\mathbb{R, Q})$ and $H(\mathbb{R, Z})$ Singular homology I presume? What have you tried? Do you have a guess? Apr 19 answered An automorphism that has no fixed points except for the identity and is its own inverse implies commutativity Apr 18 revised Units of $\mathbb Z[X]/(X^n+1)$? added 11 characters in body Apr 18 comment Units of $\mathbb Z[X]/(X^n+1)$? @Tal-Botvinnik Glad to see chess fans hanging out around here BTW. ;) Apr 18 comment Units of $\mathbb Z[X]/(X^n+1)$? @Tal-Botvinnik Sure. For instance your field contains $\mathbb Q(\sqrt 2)$ for $n>2$, and $1+\sqrt 2$ is a unit in $\mathbb Z[\sqrt 2 ]$. Apr 18 answered Units of $\mathbb Z[X]/(X^n+1)$? Apr 18 comment Rational sum of the $p$-adic series @Santiago Exactly. And the series converges for $|x|<1$, so in particular for $x=p$. Apr 18 answered Rational sum of the $p$-adic series Apr 17 comment An algebraic element $a$ in a field extension $K/F$ satisfies $a^{q^m}=a$ Hint: The field $F(a)$ is also finite, with order $q^m$ for some $m$. Apr 14 comment $p$ adic modular forms and wide open neighbourhood (e.g. Coleman primitive): is it possible to obtain a holomorphic function? I don't think so. The Coleman primitive is something truly p-adic. Apr 14 comment $p$ adic modular forms and wide open neighbourhood (e.g. Coleman primitive): is it possible to obtain a holomorphic function? So if I understand correctly, you're asking whether $p$-adic modular forms can be viewed as complex-analytic sections of the usual sheaf? Generally no, not unless the form is classical to begin with. To begin with you run into the problem that the $q$-expansion of a $p$-adic modular form is allowed to have $p$-adic coefficients, which doesn't make all that much sense over $\mathbb C$. Apr 5 comment When is $BG$ a topological group? @Qiaochu Ah. Well then I'm out of my depth. :)