# All Questions

Is there a symplectic structure on $M_{2n}(\mathbb{R})$, not necessarily with constant coefficients, such that the space of smooth invariant functions, those smooth functions $f:M_{2n}(\mathbb{... 0answers 843 views +50 ### History: What was the Lemma? (Grothendieck Harvard Lectures; Mumford) In an article about the life of Grothendieck, available here: http://www.ams.org/notices/200409/fea-grothendieck-part1.pdf Allyn Jackson writes about how Mumford was profoundly impressed: Mumford ... 1answer 210 views +50 ### Intuition behind the definition of the Siegel-Eichler transformation Recently I am reading Wall's paper "On the Orthogonal Groups of Unimodular Quadratic Forms II". In this paper, I encountered with the map$E^1_\omega$, which now I am interested in. Let$X$be an ... 1answer 162 views +150 ### Seeking very regular$\mathbb Q$-acyclic complexes This question was raised from a project with Nati Linial and Yuval Peled We are seeking a$3$-dimensional simplicial complex$K$on$12$vertices with the following properties a)$K$has a complete$...
Consider the following hierarchical (recursive) random walk model, which is also known as the hierarchical hidden Markov model in computer science. For the first level $\ell=1$, let \$\{X_t^{(\ell)}...