We prove that the augmentation variety of any positive braid Legendrian link carries a natural cluster K 2 structure. We present an algorithm to calculate the cluster seeds that correspond to the admissible Lagrangian fillings of the positive braid Legendrian links. Utilizing augmentations and cluster algebras, we develop a new framework to distinguish exact Lagrangian fillings.

Let $\mathsf {C}$ be a symmetrisable generalised Cartan matrix. We introduce four different versions of double Bott–Samelson cells for every pair of positive braids in the generalised braid group associated to $\mathsf {C}$ . We prove that the decorated double Bott–Samelson cells are smooth affine varieties, whose coordinate rings are naturally isomorphic to upper cluster algebras. We explicitly describe the Donaldson–Thomas transformations on double Bott–Samelson cells and prove that they are cluster transformations. As an application, we complete the proof of the Fock–Goncharov duality conjecture in these cases. We discover a periodicity phenomenon of the Donaldson–Thomas transformations on a family of double Bott–Samelson cells. We give a (rather simple) geometric proof of Zamolodchikov’s periodicity conjecture in the cases of $\Delta \square \mathrm {A}_r$ . When $\mathsf {C}$ is of type $\mathrm {A}$ , the double Bott–Samelson cells are isomorphic to Shende–Treumann–Zaslow’s moduli spaces of microlocal rank-1 constructible sheaves associated to Legendrian links. By counting their $\mathbb {F}_q$ -points we obtain rational functions that are Legendrian link invariants.

Let C be a symmetrizable generalized Cartan matrix. We introduce four different versions of double Bott-Samelson cells for every pair of positive braids in the generalized braid group associated to C. We prove that the decorated double Bott-Samelson cells are smooth affine varieties, whose coordinate rings are naturally isomorphic to upper cluster algebras.We explicitly describe the Donaldson-Thomas transformations on double Bott-Samelson cells and prove that they are cluster transformations. As an application, we complete the proof of the Fock-Goncharov duality conjecture in these cases. We discover a periodicity phenomenon of the Donaldson-Thomas transformations on a family of double Bott-Samelson cells. We give a (rather simple) geometric proof of Zamolodchikov's periodicity conjecture in the cases of ∆ A r .When C is of type A, the double Bott-Samelson cells are isomorphic to Shende-Treumann-Zaslow's moduli spaces of microlocal rank-1 constructible sheaves associated to Legendrian links. By counting their F q -points we obtain rational functions which are Legendrian link invariants. Contents

We introduce a decorated configuration space Conf × n (a) with a potential function W. We prove the cluster duality conjecture of Fock-Goncharov for Grassmannians, that is, the tropicalization of Conf × n (a), W canonically parametrizes a linear basis of the homogeneous coordinate ring of the Grassmannian Gr a (n) with respect to the Plücker embedding. We prove that Conf × n (a), W is equivalent to the mirror Landau-Ginzburg model of the Grassmannian considered by Eguchi-Hori-Xiong, Marsh-Rietsch and Rietsch-Williams. As an application, we show a cyclic sieving phenomenon involving plane partitions under a sequence of piecewise-linear toggles.

We show the existence of quasi-cluster A-structures and cluster Poisson structures on moduli stacks of sheaves with singular support in the alternating strand diagram of grid plabic graphs by studying the microlocal parallel transport of sheaf quantizations of Lagrangian fillings of Legendrian links. The construction is in terms of contact and symplectic topology, showing that there exists an initial seed associated to a canonical relative Lagrangian skeleton. In particular, mutable cluster A-variables are intrinsically characterized via the symplectic topology of Lagrangian fillings in terms of dually L-compressible cycles. New ingredients are introduced throughout this work, including the initial weave associated to a grid plabic graph, cluster mutation along a non-square face of a plabic graph, the concept of the sugar-free hull, and the notion of microlocal merodromy.Més lluny, heu d'anar més lluny dels arbres caiguts que ara us empresonen, i quan els haureu guanyat tingueu ben present no aturar-vos.