Abstract :
If G is a simply connected semisimple group defined over a number field k and ∞ is the set of all infinite places of k, then G has strong approximation with respect to ∞ if and only if the archimedean part of any k-simple component of the adèle group is non-compact. Using the affine Bruhat–Tits building, the authors of [W.K. Chan, J. Hsia, On almost strong approximation of algebraic groups, J. Algebra 254 (2002) 441] formulated an almost strong approximation property (ASAP) for groups of compact type, and they proved that ASAP holds for all classical groups of compact type whose Tits indices over k are not 2An(d) with d 3. In this paper, we show that ASAP holds for groups of types 3,6D4,G2,F4,E7, or E8.
