Author Archives: Persiflage

Galois Representations for non self-dual forms, Part II

Posted on April 21, 2013 by Persiflage

(Now with updates!) Let’s recap from part I. We have a Shimura variety \(Y\), a minimal projective compactification \(X\), and a (family of) smooth toroidal compactifications \(W\). We also have Galois representations of the correct shape associated to eigenclasses in … Continue reading →

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Cambridge Days

Posted on April 10, 2013 by Persiflage

Dinner at the Helmand: Zagat rating 27 (Food) and 20 (Service). After I was seated, it was fifteen minutes until I was brought a menu. Sixty seconds later, the waitress asked what I wanted to order, and then pouted when … Continue reading →

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Galois Representations for non self-dual forms, Part I

Posted on March 26, 2013 by Persiflage

This is the first of a series of posts discussing the recent work of Harris, Lan, Taylor, and Thorne on constructing Galois representations associated to regular algebraic automorphic forms for \(\mathrm{GL}(n)\) over a CM field \(F/F^{+}\). I will dispense with … Continue reading →

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Office Toys

Posted on March 22, 2013 by Persiflage

I think I need one of these for my office, possibly to point at undergraduates when they ask for a higher grade: . For the full story, see here.

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Straight from the top to the bottom

Posted on March 4, 2013 by Persiflage

Possibly the worst programme on radio is NPR’s “from the top.” Ostensibly the show is about showcasing young performers in classical music. Yet, in reality, it is all about the incredibly annoying host, Christopher O’Riley, for whom condescension has become … Continue reading →

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Stephen Fry

Posted on February 14, 2013 by Persiflage

Never let it be said that this blog shies away from confronting sacred cows. Today’s target: Stephen Fry. In the video below, Fry tries to have his cake and eat it too — calling out grammar pedants for “showing off … Continue reading →

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Torsion in the cohomology of co-compact arithmetic lattices

Posted on February 6, 2013 by Persiflage

Various authors (including Bergeron and Venkatesh) have shown that the cohomology of certain arithmetic groups have a lot of torsion. For example, if \(\Gamma\) is a co-compact arithmetic lattice in \(\mathrm{SL}_2(\mathbf{C})\), and \(\mathcal{L}\) is an acyclic local system, then \(\log … Continue reading →

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A scandal in Romania

Posted on January 28, 2013 by Persiflage

I was invited to review some research proposals for the CNCS. They offered a modest remuneration for my time (something like €168, I believe). For privacy reasons I won’t comment on the proposals I read, suffice to say that they … Continue reading →

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Small Cyclotomic Integers

Posted on January 26, 2013 by Persiflage

Julia Robinson is a famous mathematician responsible for fundamental work in logic and in particular on Hilbert’s Tenth problem. Less well known nowadays is that her husband, Raphael Robinson, was a number theorist at Berkeley. One question R.Robinson asked concerned … Continue reading →

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Random p-adic Matrices

Posted on January 23, 2013 by Persiflage

Does anyone know if the problem of random matrices over (say) \(\mathbf{Z}_p\) have been studied? Here I mean something quite specific. One could do the following, namely, since \(\mathbf{Z}_p\) is compact with a natural measure, look at random elements in … Continue reading →

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