INDAGATIONES MATHEMATICAE-NEW SERIES, cilt.18, sa.3, ss.417-420, 2007 (SCI-Expanded)
We prove that an x(0)-quasinilpotent semigroup S of continuous positive linear operators on a locally convex solid Riesz space X has a common invariant subspace. Using this, a result which implies the main theorem of Abramovich, Aliprantis and Burkinshaw [J. Funct. Anal. 115 (1993) 418-424] is also given.