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Speaker : Matthew Perlmutter
Department of Mathematics,
Univ. Tecnica de Lisboa
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Title:
REDUCED COTANGENT BUNDLES AT ZERO MOMENTUM
Abstract:
We consider the problem of cotangent bundle reduction for non free
group actions at zero momentum. We show that in this context
the symplectic stratification obtained by Sjamaar and Lerman refines
in two ways: (i) each symplectic stratum admits a stratification which
we call the secondary stratification with two distinct types of
pieces, one of which is open and dense and symplectomorphic to a
cotangent bundle; (ii) the reduced space at zero momentum admits a
finer stratification than the symplectic one into pieces that are
coisotropic in their respective symplectic strata.
We will illustrate this geometry in a simple example from mechanics.
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