Schubert Calculus and Puzzles
نویسنده
چکیده
1. Interval positroid varieties 1 1.1. Schubert varieties 1 1.2. Schubert calculus 2 1.3. First positivity result 3 1.4. Interval rank varieties 5 2. Vakil’s Littlewood-Richardson rule 7 2.1. Combinatorial shifting 7 2.2. Geometric shifting 7 2.3. Vakil’s degeneration order 9 2.4. Partial puzzles 10 3. Equivariant and Kextensions 11 3.1. K-homology 11 3.2. K-cohomology 12 3.3. Equivariant K-theory 14 3.4. Equivariant cohomology 15 4. Other partial flag manifolds 16 References 17
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THE HONEYCOMB MODEL OF GLn(C) TENSOR PRODUCTS II: PUZZLES DETERMINE FACETS OF THE LITTLEWOOD-RICHARDSON CONE
The set of possible spectra (λ, μ, ν) of zero-sum triples of Hermitian matrices forms a polyhedral cone [H], whose facets have been already studied in [Kl, HR, T, Be] in terms of Schubert calculus on Grassmannians. We give a complete determination of these facets; there is one for each triple of Grassmannian Schubert cycles intersecting in a unique point. In particular, the list of inequalities...
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