Ol'shanskii spaces for semisimple groups are special cases of ordered
symmetric spaces. The theory of spherical functions on semisimple Ol's
hanskii spaces is extended to general Ol'shanskii spaces. The detailed
structure theory for Lie algebras with invariant cones is used to gen
eralize geometric results for Ol'shanskii spaces. Spherical functions
are then defined via a set of integral equations using a Volterra alge
bra that consists of G-invariant kernels satisfying a causality condit
ion. It is shown that the resulting integral spherical formulas suffic
e to build a spherical Laplace transform and an inversion formula for
this transform. (C) 1996 Academic Press, Inc.