Category Archives: Mathematics

Local representations occurring in cohomology

Posted on November 5, 2013 by Persiflage

Michael Harris was in town for a few days, and we chatted about the relationship between my conjectures on completed cohomology groups with Emerton and the recent work of Scholze. The brief summary is that Scholze’s results are not naively … Continue reading →

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Abelian Varieties

Posted on October 30, 2013 by Persiflage

Jerry Wang gave a nice talk this week on his generalization of Manjul’s work on pointless hyperelliptic curves to hyperelliptic curves with no points over any field of odd degree (equivalently, \(\mathrm{Pic}^1\) is pointless). This work (link here) is joint … Continue reading →

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Who is D.H.J. Polymath?

Posted on October 20, 2013 by Persiflage

D.H.J. Polymath is the assumed collective pseudonym for the authors of a number of papers which have arisen as a result of the polymath project initated by Gowers. Presumably, since it is a matter of open record, one can go … Continue reading →

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Why is my paper taking so long to review?

Posted on October 1, 2013 by Persiflage

The question in the title does not refer to any of my own papers; rather, I want to *answer* the question from the perspective of an editor. Here, roughly, is how the sausage is made (this is a medium case … Continue reading →

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Virtual Congruence Betti Numbers

Posted on September 27, 2013 by Persiflage

Suppose that \(G\) is a real semisimple group and that \(X = \Gamma \backslash G/K\) is a compact arithmetic locally symmetric space. Let us call a cohomology class tautological if it is invariant under the group \(G\). For example, if … Continue reading →

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Life on the modular curve

Posted on September 24, 2013 by Persiflage

Alice and Bob live on the modular curve \(X_0(1) = \mathbf{H}/\mathrm{PSL}_2(\mathbb{Z})\). What does the world look like to them, assuming that they view the world in hyperbolic perspective? To those who are not used to hyperbolic geometry, there may be … Continue reading →

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En Passant III

Posted on August 31, 2013 by Persiflage

Question: When you are sick in bed, can you do any mathematics? I just spent the past few weeks with a sinus infection and was completely unable to do anything productive, that is, apart from writing an NSF grant (which … Continue reading →

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The Fundamental Curve of p-adic Hodge Theory, Part II

Posted on August 12, 2013 by Persiflage

This is a second post from JW, following on from Part I. The Galois group of \(\mathbb{Q}_p\) as a geometric fundamental group. In this follow-up post, I’d like to relay something Peter Scholze told me last fall. It concerns the … Continue reading →

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The Fundamental Curve of p-adic Hodge Theory, or How to Un-tilt a Tilted Field

Posted on July 23, 2013 by Persiflage

As Quomodocumque once said concerning the most recent set of courses at Arizona Winter School, “Jared Weinstein [gives] a great lecture.” On that note, I am delighted to welcome our first guest post, by the man himself. Note that it … Continue reading →

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Effective Motives

Posted on July 3, 2013 by Persiflage

This is a brief follow up concerning a question asked by Felipe. Suppose we assume the standard conjectures. Let \(M\) be a pure motive, and consider the following problems: Problem A: (“effectivity”) Suppose that \(M\) has non-negative Hodge-Tate weights. Then … Continue reading →

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