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David Loeffler's user avatar
David Loeffler's user avatar
David Loeffler's user avatar
David Loeffler
  • Member for 15 years
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Gysin isomorphism in de Rham cohomology using currents
There's a pullback (restriction) map on differential forms $\Omega^j_X \to \Omega^j_Z$, and it sends compactly-supported forms to compactly-supported forms. Now just define the map $D^i_Z \to D^{i+r}_X$ to be the dual of this. No need to even mention $\delta_Z$.
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Gysin isomorphism in de Rham cohomology using currents
Just a suggestion: have you tried considering maps $D^i_Z \to D^{i+r}_X$, rather than $\Omega^i_Z \to \Omega^{i+r}_X$?
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Orbit of a parahoric subgroup on a flag variety
(sorry, I posted a comment but it was nonsense). This looks great, thanks!
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Number of imaginary quadratic field with its ideal class group has $\Bbb{Z}/2\Bbb{Z}$ as 2 part
@WillJagy I've added a clarification of exactly what I'm answering (since the title of the question, the first paragraph of the question, and the final paragraph are actually asking three distinct questions)
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Computations of half-integer forms in SAGE/Magma
I'd be very surprised if this were implemented, it's already pretty difficult to compute the action of Atkin--Lehner operators in integer weight (there are no simple formulas for the action in terms of q-expansions).
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Are rigid-analytic spaces obsolete, since adic spaces exist?
Incidentally, I was working in p-adic automorphic forms / eigenvarieties roughly between 2005 and 2012. During this time, I read many, many papers, and wrote a fair number myself, in which Tate-style rigid spaces appeared. I can count on one hand the number of times I encountered Berkovich spaces during this period. (Do not fall into the trap of judging what was "generally known" at some point in the past from a few landmark papers of that time that are widely read nowadays; these are, by definition, unrepresentative of the time they were written.)
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Are rigid-analytic spaces obsolete, since adic spaces exist?
I disagree with your claim that "Berkovich spaces were what was supplanted by adic spaces after Scholze popularized them, rigid spaces as originally defined had already fallen out of favor for many". During the decade or so prior to Scholze's arrival on the scene, Berkovich spaces were used in some areas as an alternative to classical rigid spaces, but they never came near supplanting classical rigid spaces across the board, as adic spaces later did.
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Orbit of a parahoric subgroup on a flag variety
I wouldn't go that far, it's definitely helpful to have a reference, and the general setting of "double Tits systems" considered loc. cit. does sound as if it might be relevant for my general question.
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