The totally nonnegative Grassmannian is a ball. (English) Zbl 1482.05355
Summary: We prove that three spaces of importance in topological combinatorics are homeomorphic to closed balls: the totally nonnegative Grassmannian, the compactification of the space of electrical networks, and the cyclically symmetric amplituhedron.
MSC:
| 05E45 | Combinatorial aspects of simplicial complexes |
| 14M15 | Grassmannians, Schubert varieties, flag manifolds |
| 15B48 | Positive matrices and their generalizations; cones of matrices |
| 52B99 | Polytopes and polyhedra |
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