Flattenings and Koszul Young flattenings arising in complexity theory

Abstract: I find new equations for Chow varieties, their secant varieties, and an additional variety that arises in the study of depth 5 circuits by flattenings and Koszul Young flattenings. This enables a new lower bound for symmetric border rank of $x_1x_2\cdots x_d$ when $d$ is odd, and a lower bound on the size of depth 5 circuits that compute the permanent.