This is an old revision of the document!
2023-03-29
6 hours.
- skeleton for hypertoric base mfd.
- implement the idea of path conormal.
- exact WKB, what's going on.
Skeleton
Reading Gammage-Mcbreen-Webster again, I notice that they indeed would require unimodular. But their phrasing of unimodularity is a bit strange. they require the projections to these coordinates.
It is understandable, because the basic model, $\C^n$ has a prefered factorization, so we only have $S_n$ symmetry. Instead of having the full $GL(n,\Z)$ symmetry. No, that is not a valid argument. Even the usual mirror symmetry for $\C^n$, has a favorite cone.
Suppose I want to have $\C^*$ act on $\C^3$ by weight $(2,3,5)$. This is an example where it is not unimodular. Let's see what would be wrong.
Consider the classical mirror symmetry for toric variety, here we would get $\P^2_{2,3,5}$, a not so bad smooth DM stack. It's mirror is just fine. We can use GIT to know its skeleton.
And, from the partition information on the 2-torus, we should be able to reconstruct the moment polytope, hence build the corresponding toric variety.
Consider a simpler example, $\C^*$ acting on $\C^2$ with weight $(1,2)$. We know what's the mirror is. Now, the question is, what the story on the multiplicative side? OK, we run Gale duality, we have $$ L \xto{(1,2)} \Z^2 \xto{(2,-1)} N $$ $L= \Z$, and the quotient is $N=\Z$ again, no problem.
The Gale dual is somehow isomorphis, up to a sign change. The other example is similar, any primitive vector can be completed to a $\Z$-basis. The correct condition should be saturated. Anyway.
In the weight $(1,2)$ case, we need to quotient out $(T^*\C^2)^o$, with variables $(x_1, y_1, x_2, y_2)$. We have complex moment map condition being $$ (x_1 y_1 + 1) (x_2 y_2 + 1)^2 = \beta $$ for some generic $\beta \in \C^*$. And then, we just take the usual GIT quotient, quotient by $\C^*$.