“…Actually, if G is a connected and simply connected Lie group over the field of real numbers whose Lie algebra is g, then there is a left-invariant flat and torsion free connection, that is, an affine structure on G if and only if g has a compatible left-symmetric algebra ( [13,14]). There are a lot of papers addressing the compatible left-symmetric algebras on a given Lie algebra (see [8,12,3,6,2]). In particular, an important result given by Chu [5] asserts that there do not exist any compatible left-symmetric algebra on a complex finite-dimensional semisimple Lie algebra.…”