A building-theoretic approach to relative Tamagawa numbers of quasi-split semisimple groups over global function fields

Abstract

Let G be a semisimple quasi-split group defined over a global function field. We express the relative Tamagawa number of G in terms of local data including the number of types of special vertices in one orbit of the Bruhat-Tits building over some completion with respect to a place and the class number of G at that place.