Li Ping HUANG
Let D be any division ring,and let T(mi,ni,k)be the set of k×k(k≥2)rectangular block triangular matrices over D.For A,B∈T(mi,ni,k),if rank(A-B)=1,then A and B are said to be adjacent and denoted by A~B.A mapφ:T(mi,ni,k)→T(mi,ni,k)is said to be an adjacency preserving map in both directions if A~B if and only ifφ(A)~φ(B).Let G be the transformation group of all adjacency preserving bijections in both directions on T(mi,ni,k).When m1,nk≥2,we characterize the algebraic structure of G,and obtain the fundamental theorem of rectangular block triangular matrices over D.