Category Archives: Uncategorized

ArXiv x 3

Posted on March 4, 2022 by Persiflage

Three recent arXiv preprints this week caught my interest and seemed worth mentioning here. The first is a paper by Oscar Randal-Williams, which considers (among other things) the cohomology of congruence subgroups of \(\mathrm{SL}_N(\mathbf{Z})\) in the stable range. This is … Continue reading →

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Tips on becoming a computational number theorist

Posted on June 16, 2020 by Persiflage

How would you advise a student who has talents in both the computational and theoretical aspects of algebraic number theory? There is no hard border between computational and theoretical algebraic number theory, but there is a definite computational number theory … Continue reading →

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More on Lehmer’s Conjecture

Posted on March 21, 2020 by Persiflage

Lehmer said it was a “natural question” whether there existed an integer such that \(\tau(n)=0\) or not. I’ve wondered a little bit recently about how reasonable this is. (See this post.) The historical context is presumably related to the fact … Continue reading →

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Background for the Hausdorff Summer School

Posted on December 20, 2019 by Persiflage

For those attending the Haussdorf Summer School previously mentioned here, I followed up with the speakers to ask them a little about what background was optimal for getting the most out of their lectures. In particular, I asked them to … Continue reading →

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NSF Application Tips: LaTeX edition

Posted on September 6, 2019 by Persiflage

I’ve previously written about applying for an NSF grant here. But for those applying this year, I have a few further technical tips concerning the technical specifications of your LaTeX document. If you are the type of person who uploads … Continue reading →

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Administrative Note

Posted on September 5, 2019 by Persiflage

Ideally nobody will really notice, but this blog has moved from www.galoisrepresentations.wordpress.com to www.galoisrepresentations.com. This blog still runs on the (open source) wordpress system, the only difference is that it is longer hosted by wordpress. The reason for hosting this … Continue reading →

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The stable cohomology of SL(F_p)

Posted on June 19, 2019 by Persiflage

Back by popular demand: an actual mathematics post! Today’s problem is the following: compute the cohomology of \(\mathrm{SL}(\mathbf{F}_p)\) for a (mod-p) algebraic representation. Step 0 is to say what this problem actually is. It makes sense to talk about certain … Continue reading →

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Referee Requests

Posted on April 11, 2019 by Persiflage

################################################### From: Mathematics Editorial Office Subject: [Mathematics] Review Request Date: December 26, 2018 at 7:43:31 AM CST Dear Professor Calegari, Happy new year. We have received the following manuscript to be considered for publication in Mathematics (http://www.mdpi.com/journal/mathematics/) and kindly invite … Continue reading →

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Local-global compatibility for imaginary quadratic fields

Posted on January 16, 2019 by Persiflage

One of the key steps in the 10-author paper is to prove results on local-global compatibility for Galois representations associated to torsion classes. The results proved in that paper, unfortunately, fall well-short of the optimal desired local-global compatibility statement, because … Continue reading →

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Jacquet-Langlands and an old R=T conjecture

Posted on January 12, 2019 by Persiflage

This is part 2 of a series of posts on R=T conjectures for inner forms of GL(2). (See here for part 1). (Edit: this is still incorrect and there should have been a part 3, but I’ve been distracted… in … Continue reading →

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