The cluster-algebra tropical fan conjecture

From papers

Let A\mathcal{A} be a cluster algebra of finite type over R\mathbb{R}, let CC be its coefficient-variable set, and let S(A)S(\mathcal{A}) be its associated cluster complex. Consider the positive tropical variety Trop+SpecA\operatorname{Trop}^+ \operatorname{Spec} \mathcal{A} and its lineality space.

Tropical fan conjecture. If the lineality space of Trop+SpecA\operatorname{Trop}^+ \operatorname{Spec} \mathcal{A} has dimension C|C|, then the quotient of Trop+SpecA\operatorname{Trop}^+ \operatorname{Spec} \mathcal{A} by its lineality space is a simplicial fan abstractly isomorphic to the cone over S(A)S(\mathcal{A}). If this dimension condition does not hold, the resulting fan is a coarsening of the cone over S(A)S(\mathcal{A}).

This conjecture proposes that using enough coefficient variables recovers the full cluster complex from the positive tropical variety, while insufficient coefficients produce a coarsening. The statement is motivated by the finite-type Grassmannian examples and by the observed failure for the coefficient-specialized cluster algebra of Gr2,6Gr_{2,6}; its general status is not established in the supplied source.

Progress summary

Nothing recorded yet. Refresh searches the literature and the public web for attempts on this problem, and writes the first summary here.

Sources & referencesView supporting material

Primary source

David Speyer and Lauren K. Williams, “The tropical totally positive Grassmannian”, arXiv:math/0312297 (2003).

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