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Full-Text Articles in Physical Sciences and Mathematics
A Polytope Combinatorics For Semisimple Groups, Jared E. Anderson
A Polytope Combinatorics For Semisimple Groups, Jared E. Anderson
Mathematics and Statistics Department Faculty Publication Series
Mirkovi and Vilonen discovered a canonical basis of algebraic cycles for the intersection homology of (the closures of the strata of) the loop Grassmannian. The moment map images of these varieties are a collection of polytopes, and they may be used to compute weight multiplicities and tensor product multiplicities for representations of a semisimple group. The polytopes are explicitly described for a few low rank groups.
Bilinear Operators With Non-Smooth Symbol, I, John E. Gilbert, Andrea R. Nahmod
Bilinear Operators With Non-Smooth Symbol, I, John E. Gilbert, Andrea R. Nahmod
Mathematics and Statistics Department Faculty Publication Series
This paper proves the Lp-boundedness of general bilinear operators associated to a symbol or multiplier which need not be smooth. The Main Theorem establishes a general result for multipliers that are allowed to have singularities along the edges of a cone as well as possibly at its vertex. It thus unifies ealier results of Coifman-Meyer for smooth multipliers and ones, such the Bilinear Hilbert transform of Lacey-Thiele, where the multiplier is not smooth. Using a Whitney decomposition in the Fourier plane a general bilinear operator is represented as infinite discrete sums of time-frequency paraproducts obtained by associating wave-packets with tiles …