Department of Mathematics FAS Harvard University One Oxford Street Cambridge MA 02138 USA Tel: (617) 495-2171 Fax: (617) 495-5132
To post a seminar which takes place at the Mathematics department, please email seminars@math.harvard.edu with date, time, room, title and possibly with an abstract.
DIFFERENTIAL GEOMETRY SEMINAR: Yong Lin
Renmin University
Heat kernel estimate and solution of semi linear heat equations on graphs
on Tuesday, January 24, 2017, at 4:15 pm in Science Center 507
We prove the heat kernel lower estimate on graphs under volume growth condition. By using this heat kernel estimate and curvature assumption, we prove the existence and nonexistence results of global solutions for the semilinear heat equation on graphs. --Organized by Professor Shing-Tung Yau

CENTER OF MATHEMATICAL SCIENCES AND APPLICATIONS MATHEMATICAL PHYSICS SEMINAR: Yu Qiu
Chinese University of Hong Kong
Spherical twists on 3-Calabi-Yau categories of quivers with potentials from surfaces and spaces of stability conditions
on Monday, January 30, 2017, at 12:00 pm in CMSA Building, 20 Garden St, G10
We study the 3-Calabi-Yau category D(S) associated to a marked surface S. In the case when S is unpunctured, we show that the spherical twist group, which is a subgroup of auto-equivalence group of D(S), is isomorphic to a subgroup of the mapping class group of S_Delta--the decorated version of S. In the case when S is an annulus, we prove that the space Stab of stability conditions on D(S) is contractible. We also present working progress on proving the simply connectedness of Stab for any unpunctured case and on studying Stab for the punctured case.

DIFFERENTIAL GEOMETRY SEMINAR: Yu Qiu
Chinese University of Hong Kong
Stability conditions for quivers via exchange graphs
on Tuesday, January 31, 2017, at 4:15 pm in Science Center 507
Let Q be an acyclic quiver and D_N(Q) be the associated N-Calabi-Yau category. We (with Alastair King) show that the quotient graph of the exchange graph of hearts/t-structures in D_N(Q) by the spherical twists is isomorphic to the (N-1)-cluster exchange graph. In the case when Q is of Dynkin type, we (with Jon woolf) show that the spherical twist group is isomorphic to the braid group of Q and the corresponding (principal component of) space of stability conditions is contractible. Organized by Prof. Shing-Tung Yau

CENTER OF MATHEMATICAL SCIENCES AND APPLICATIONS COLLOQUIUM: Sean Eddy
Harvard Dept of Molecular and Cellular Biology
Biological sequence homology searches: the future of deciphering the past
on Wednesday, February 01, 2017, at 4:30 pm in CMSA Building, 20 Garden St, G10
Computational recognition of distant common ancestry of biological sequences is a key to studying ancient events in molecular evolution. The better our sequence analysis methods are, the deeper in evolutionary time we can see. A major aim in the field is to improve the resolution of homology recognition methods by building increasingly realistic, complex, parameter-rich models. I will describe current and future research in homology search algorithms based on probabilistic inference methods, using hidden Markov models (HMMs) and stochastic context-free grammars (SCFGs). We make these methods available in the HMMER and Infernal software from my laboratory, in collaboration with database teams at the European Bioinformatics Institute in the UK.

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