On the number of abelian left symmetric algebras

In this paper we prove that there are infinitely many abelian left symmetric algebras in dimensions . Equivalently this means that there are, up to affine conjugation, infinitely many simply transitive affine actions of , for . This is a result which is usually credited to A.T. Vasquez, but for which there is no proof in the literature.

     

Finite 2‐Geodesic Transitive Graphs of Prime Valency

We classify noncomplete prime valency graphs satisfying the property that their automorphism group is transitive on both the set of arcs and the set of 2‐geodesics. We prove that either Γ is 2‐arc transitive or the valency p satisfies , and for each such prime there is a unique graph with this property: it is a nonbipartite antipodal double cover of the complete graph with automorphism group and diameter 3.     

Flag‐Transitive 2‐ Symmetric Designs with Sporadic Socle

Let be a nontrivial 2‐ symmetric design admitting a flag‐transitive, point‐primitive automorphism group G of almost simple type with sporadic socle. We prove that there are up to isomorphism six designs, and must be one of the following: a 2‐(144, 66, 30) design with or , a 2‐(176, 50, 14) design with , a 2‐(176, 126, 90) design with or , or a 2‐(14,080, 12,636, 11,340) design with .     

疯狂动力系统的一些性质

针对纤维映射为旋转的疯狂动力系统,比较系统的研究了它们的回复性、混合性、混沌性等基本的动力学性质.