We revisit localisation and patching method in the setting of Chevalley groups. Introducing certain subgroups of relative elementary Chevalley groups, we develop relative versions of the conjugation calculus and the commutator calculus in Chevalley groups G(Φ, R), rk(Φ) ≥ 2, which are both more general, and substantially easier than the ones available in the literature. For classical groups such relative commutator calculus has been recently developed by the authors in [34,33]. As an application we prove the mixed commutator formula,for two ideals a, b R. This answers a problem posed in a paper by Alexei Stepanov and the second author.
O Life, you put thousand traps in my wayDare to try, is what you clearly say Omar Khayam
IntroductionOne of the most powerful ideas in the study of groups of points of reductive groups over rings is localisation. It allows to reduce many important problems over arbitrary commutative rings, to similar problems for semi-local rings. Localisation comes in a number of versions. The two most familiar ones are localisation and patching, proposed by Daniel Quillen [55] and Andrei Suslin [65], and localisationcompletion, proposed by Anthony Bak [8].Originally, the above papers addressed the case of the general linear group GL(n, R). Soon thereafter, Suslin himself, Vyacheslav Kopeiko, Marat Tulenbaev, Giovanni Taddei, Leonid Vaserstein, Li Fuan, Eiichi Abe, You Hong, and others proposed workingThe work of the second author was supported by RFFI projects