Stratified Morse critical points and Brasselet number on toric varieties (2004.13793v1)

Abstract: The generalization of the Morse theory presented by Goresky and MacPherson is a landmark that divided completely the topological and geo-me-tri-cal study of singular spaces. In this work, we consider $(X,0)$ a germ at $0$ of toric variety and non-degenerate function-germs $f,g : (X,0) \to (\mathbb{C},0)$, and we prove that the difference of the Brasselet numbers ${\rm B}{f,X}(0)$ and ${\rm B}{f,X\cap g^{-1}(0)}(0)$ is related with the number of Morse critical points {on the regular part of the Milnor fiber} of $f$ appearing in a morsefication of $g$, even in the case where $g$ has a critical locus with arbitrary dimension. This result connects topological and geometric properties and allows us to determine many interesting formulae, mainly in therms of the combinatorial information of the toric varieties.