On holomorphic Lagrangians

Hi, I really enjoyed Vivek’s talk and our discussions, which prompted me to come back here and discover a half-finished post from a while ago; let me finish it now. Let $C$ be a Riemann surface. Let $\Sigma \subset T^* C$ be a complex curve (we think of it as a spectral curve for a Hitchin system on $C$.) …

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notes from all around

Recall that given a collection of curves $C_i$ on a surface $\Sigma$, we construct a 4-manifold $W$ by Weinstein handle attachment of disks to $T^* \Sigma$ along the Legendrian lifts of the $C_i$.  It contains a Lagrangian skeleton $\mathbb{L}$, formed as the union of $\Sigma$, the positive conormals to the $C_i$ and the 2-d disks $D_i$ …

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Cluster algebras from curves on surfaces

The unmentioned context for David T.’s previous post is the following conjecture of mine. Construction.  Let $S$ be a surface, and $C_i$ be oriented simple curves on it.  Lift the $C_i$ to Legendrians on the cocircle bundle by taking the positive conormal.  Form a symplectic 4-manifold $M$ by Weinstein handle attachment to the lifts of the …

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2d ribbon graphs

Let $S$ be a surface, let $\Lambda = \{\lambda_i\}_{i \in I}$ be a Legendrian link in $T^{\infty} S$ with components $\lambda_i$.  Write $\phi_i \subset S$ for the front projection of $\lambda_i$.  Write $\underline{\Lambda} \subset T^* S$ for the conic Lagrangian obtained by coning off $\Lambda$ and taking the union with the zero section. Let $M$ …

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Bezrukavnikov-Kapranov

They’ve discovered what Eric and Nicolo and I call “the constructible plumbing model”, for Riemann surfaces glued transversely. In the first and last sections they seem to envision many of the same applications. I haven’t read the middle yet. arXiv:1506.07050

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Notes from the second square

This last week, a bunch of us met at AIM for the second meeting of a square.  The first meeting was where we proved “augmentations are sheaves [NRSSZ]“.  This time we talked about some related things, and also began a dialogue about what the contact/symplectic geometry has to say about the cluster charts structure on the moduli …

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F-fields

Definition.  Fix a prime $p$.  Let $M$ be a manifold.  An $F$-field on $M$ is a locally constant sheaf of perfect rings of characteristic $p$. Each element of $H^1(M,\mathbf{Z})$ determines an isomorphism class of $F$-fields.  The $F$-field $\mathfrak{f}$ corresponding to the cocycle $z$ has one fiber that is $\overline{\mathbf{F}_p}$, and each loop in $M$ acts …

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