Title: Sharp restriction estimates for several degenerate higher co-dimensional quadratic surfaces

Abstract: Fourier restriction conjecture is an important problem in harmonic analysis. Guo-Oh [17] studied the restriction estimates for quadratic surfaces of co-dimension 2 in $\mathbb{R}^5$. For one special surface $(\xi_1,\xi_2,\xi_3,\xi_1^2,\xi_2^2+\xi_1\xi_3)$, they applied a nested induction argument to build essentially sharp restriction estimate. In this paper, we simplify their method, and extend it to a variant of the broad-narrow analysis. As applications, we will prove essentially sharp restriction estimates for some kinds of degenerate higher co-dimensional quadratic surfaces.