Plethysm and Lattice Point Counting
summary
Computes plethysm characters by translating coefficients to lattice-point counts in polytopes and uses Barvinok via the ISL library to get explicit chamber decompositions and quasi-polynomial formulas; produces parametric formulas in k for many outer partitions including s_mu of S^k up to |mu|=5, with fast evaluation even for huge numeric inputs. Identifies the leading term from polytope volume matching Pieri/Littlewood–Richardson intuition, and notes bottlenecks in human-readable postprocessing and formula minimization.
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