It is known from
Markov-Kakutani theorem that if Tj(j = 1,2,⋯,J) are continuous affine
commuting self-mappings on a compact convex subset of a locally convex
space, then the intersection of the sets of fixed points of Tf(j = 1,2,⋯,J) is
nonempty. The object of this paper is to show a result which says more than the
above theorem does, and actually our theorem shows in the case of J = 2
that the set of fixed points of λT1+ (1 − λ)T2 always coincides, for each
λ(0 < λ < 1), with the intersection of the sets of fixed points of T1 and
T2.