Monthly Archives: September 2013

Virtual Congruence Betti Numbers

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

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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Parenthood

Some questions, I guess, one can’t be prepared for:

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