Mari˜no -vafa Formula and Hodge Integral Identities

Based on string duality Mariño and Vafa [10] conjectured a closed formula on certain Hodge integrals in terms of representations of symmetric groups. This formula was first explicitly written down by the third author in [13] and proved in joint work [8] of the authors of the present paper. For a different approach see [12]. Our proof follows the strategy of proving both sides of the equation satisfy the same cut-and-join equation and have the same initial values. In this note we will describe a proof of the ELSV formula relating Hurwitz numbers and Hodge integrals: