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--- blog:2023-05-07 [2023/05/07 17:26] – pzhou
+++ blog:2023-05-07 [2023/06/25 15:53] (current) – external edit 127.0.0.1
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   * paper by Oblomkov-Rozansky, about matrix factorization, B-model realization of the Hecke category.
+===== Signs and Orientations =====
+  * we choose orientation for each strands in each Lagrangians.
+  * I don't know what is a relative spin structure.
+  * something about capping for each intersection.
+Their Lagrangians are union of spheres. They want a trivial $\R$ bundle on the space, so that the direct sum of $\R$ with the tangent bundle is trivial. (well, sometimes, a bundle is stably trivial, you just need to give it more rooms).
+We choose trivialization $t$ and $t'$ for the two 'augmented' Lagrangian (are they jet bundle?).
+A capping Lagrangian path in the **oriented** Lagrangians Grassmannian. (so, do I choose orientation of my Lagrangians? I guess I did, since I have trivializations, and I can substract that trivial line bundle.)
+A stable capping trivialization is a trivialization of the capping path $L_{p,t} \oplus \R$, that interpolate the original trivializations on the two strands.
+OK, these are the data. How do I provides orientation for the moduli spaces then?
+We map the upper half-plane to the target space. actually, it is a constant map (what?) to $p$, and we consider the trivial vector bundle $\pi_p^*(T_p M)$. We define the Cauchy-Riemann tuple. $\xi, \eta, D$
+  * $\xi$ is the symplectic constant vector bundle over $H$.
+  * on the boundary $\d H$, we segment it into $(-\infty, 0), (0,1), (1,\infty)$, and we put the **oriented** Lagrangian sub-bundle $\eta$ over $\d H$.
+  * A Cauchy-Riemann operator, that takes as input a section in the symplectic bundle $\xi$, and output its dbar derivative? OK, I am not sure.
+well, a determinant line is a kernel minus cokernel, taking determinants.
+===== What is orientation? =====
+If $L$ satisfies certain topological condition, then the moduli space of disks ending on $L$ is orientable.
+But, how do we define the A-infinity structures? Why we count some disks with a negative sign? When we say we orient the 0-dim moduli space of the disks, that means plus-minus signs.