TY - JOUR ID - 31460 TI - A CHARACTERIZATION OF EXTREMELY AMENABLE SEMIGROUPS JO - Journal of Sciences, Islamic Republic of Iran JA - JSCIENCES LA - en SN - 1016-1104 Y1 - 1990 PY - 1990 VL - 1 IS - 4 SP - EP - DO - N2 - Let S be a discrete semigroup, m (S) the space of all bounded real functions on S with the usualsupremum norm. Let Acm (S) be a uniformly closed left invariant subalgebra of m (S) with 1 c A. We say that A is extremely left amenable if there isamultiplicative left invariant meanon A. Let P = {h ?A: h =|g-1,g | forsome g ?A, s ?S}. It isshown that . A is extremely left amenable if and only if there is a mean ? on A such that ?(PA) = 0. UR - https://jsciences.ut.ac.ir/article_31460.html L1 - https://jsciences.ut.ac.ir/article_31460_8adab8d1ba3a4f8a163ddf0624182fb4.pdf ER -