I am wondering, nobody can read the mathematics and come up with what Grothendieck meant !!! after all, this is not philosophy or psicology !! Andrew Stacey wrote:
On Mon, Aug 30, 2010 at 10:18:30AM -0400, Michael Barr wrote:
Grothendieck introduces, on the top of p. 209 of the Tohoku paper, the notation U_{i_0..i_p} without explanation and uses it again over the next couple pages. Here {U_i} is an open cover of a space X and I have reason to believe that this stands for the intersection of U_{i_j}. Can anyone confirm this? Or give an alternate explanation?
The context is that of a claim that (when A is a sheaf) and "every U_{i_0..i_p} is A-acyclic, then"... and that awfully like the definition of a simple cover.
I have absolutely no idea as to what Grothendieck meant, but the notation you describe is quite common in (algebraic) topology and means what you "have reason to believe" that it means.
Andrew
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