MATH Seminar

Title: Transversality defect of two lagrangians and ternary index. Application: Formulas of (non) additivity of signatures and of linking forms
Seminar: Algebra
Speaker: Jean Barge of Ecole polytechnique
Contact: David Zureick-Brown, dzb@mathcs.emory.edu
Date: 2014-04-29 at 4:00PM
Venue: W302
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Abstract: (This is a common work with Jean Lannes) To a pair of lagrangians in a symplectic space, we associate a symetric bilinear form well defined up to the addition of non-degenerate forms and which is itself non-degenerate if and only if the two lagrangians are transversal. To a triple of lagrangians, we associate a ternary index which is a raffinement of the Leray-Kashiwara index and which generalizes for any (commutative) ring the index defined by Wall for fields. We will explain how these two invariants can be used to compute signatures and linking forms of manifolds obtained by gluing.