5,600 reputation
1943
bio website math.stanford.edu/~church
location Stanford
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visits member for 5 years, 7 months
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2d
comment Searching for $C^*$
This is clearly a question of interest to research mathematicians (indeed uniquely to research mathematicians).
May
21
comment Will this be a case of self plagiarism or will it annoy the referee?
I'm voting to close this question as off-topic because it belongs on academia.stackexchange.com (and was also asked there: academia.stackexchange.com/questions/45754/…)
May
16
comment Generalize $\pi_0(B\mathcal{C})\cong\{\text{objects}\}/\{\text{morphisms}\}$ to categories internal to topological spaces
The proof you give is not correct. Consider the category $x\rightarrow y\leftarrow z$. There is a path in $B\mathcal{C}$ from $x$ to $z$, but there is no morphism in $\mathcal{C}$ from $x$ to $z$. This contradicts your claim "which means that there is a morphism between x0 and x1"; the mistake seems to be in the earlier claim "yields a path ... but as $N_1(\mathcal{C}) is discrete, it is constant". As Zhen Lin points out, the correct deduction is that there is a zigzag of morphisms from $x_0$ to $x_1$.
Apr
29
comment Continuous maps to fat geometric realizations of simplicial spaces
Note there is a typo in the statement of Segal's Proposition 4.1: it should say that $\text{pr}\colon BX_U\to X$ is a homotopy equivalence, not $BR_U\to X$.
Apr
28
awarded  Revival
Mar
25
reviewed Approve Can an abelian variety/Q have no non-trivial points over Q_sol?
Mar
24
reviewed Approve Mal'cev “rational equivalence” and model theory
Mar
18
reviewed Approve hyperbolic metrics
Mar
15
answered Does there exist a fibre bundle $K(\mathbb{Z}_4,1)\rightarrow K(\mathbb{Z}_2,1)$ with fiber $K(\mathbb{Z}_2,1)$?
Mar
6
answered Maryam Mirzakhani's works
Mar
6
reviewed Approve latex tag wiki
Feb
26
comment $G_\mathbb{Z}$-homotopy type of rational Tits building $\Delta_{G, \mathbb{Q}}$
@J.Martel: We're considering the usual cellular homology of these buildings with integer coefficients, without interference from any groups at all.
Feb
26
revised $G_\mathbb{Z}$-homotopy type of rational Tits building $\Delta_{G, \mathbb{Q}}$
add reference to paper arXiv:1501.01307, now that it is posted
Feb
26
reviewed Approve matrix-theory tag wiki excerpt
Feb
24
awarded  Excavator
Feb
24
revised Example of a Group which has $\text{SL}_{n}(\mathbb{Z})$ as the automorphism group
added Oliver Baues to author list (and added links to arXiv, MathReviews and journal)
Feb
3
reviewed Leave Open Is there any Lefschetz-like principle for representations of finite groups?
Feb
3
reviewed Leave Open Direct product of filters
Feb
3
reviewed Leave Open Propositional logic: Minimal set of formulas, which is consistent and complete
Feb
3
reviewed Leave Open integral or rational cohomology of real grassmannians