Independence of l and local terms

Independence of l and local terms

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Martin Olsson, University of California - Berkeley
IAS Room S-101

Let $k$ be an algebraically closed field and let $c:C\rightarrow X\times X$ be a correspondence. Let $\ell $ be a prime invertible in $k$ and let $K\in D^b_c(X, \overline {\mathbb{Q}}_\ell )$ be a complex. An action of $c$ on $K$ is by definition a map $u:c_1^*K\rightarrow c_2^!K$. For such an action one can define for each proper component $Z$ of the fixed point scheme of $c$ a local term $\text{lt}_Z(K, u)\in \overline {\mathbb{Q}}_\ell $. In this talk I will discuss various techniques for studying these local terms and some independence of $\ell $ results for them. I will also discuss consequences for traces of correspondences acting on cohomology