Peng Zhou

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blog:2023-01-27

2023-01-27 End of AIM workshop

  • [AK]: Vector Bundle on $\P^2$
  • [EG]: Affine Springer Fiber
  • [WL]: Ruling and Stratification

Vector Bundles on $\P^2$

It is always a good idea to share your thoughts, it might induce more sparks.

We follow Knutson and Sharpe.

Consider the moduli space of rank $n$ vector bundles on $\P^2$. It is given by a disjoint union of components, labelled by $(\lambda, \mu, \nu) \in (X^*(T)/W)^3$, dominant weights $$ (L_\lambda \times L_\mu \times L_\nu) / GL(n) $$ where $L_\chi$ is the equivariant line bundle over the flag variety $GL_n/B$.

First, we recall Klyacho's description of toric vector bundle on $\P^2$. Consider $v_1, v_2, v_3 \in N$ the three ray generators of the toric fan. Let $D_1, D_2, D_3$ be the corresponding divisor. The subtorus $T_i$ for $v_i$ fixes $D_i$. Consider the vector bundle $E$ on $\P^2$, we have $T_i$ acting on $E|_{D_i}$, with weights. They give me a collection of hyperplanes.

Now, we can consider the restriction of $E$ over the torus fixed points. Here is Klyacho's 'filtration description' of a toric vector bundle.

So, why we have a filtration? We can say, if we do restriction to fixed, points, we get a weight decomposition of the fiber over there. More generally, we get a multi-polytope, as shown in Sam Payne's paper

How does this compare with the configuration space of decorated flags?

blog/2023-01-27.txt · Last modified: 2023/06/25 15:53 by 127.0.0.1