in the first part of this paper, some theorems are given for a riemannian manifold with semi-symmetric metric connection. in the second part of it, some special vector fields, for example, torse-forming vector fields, recurrent vector fields and concurrent vector fields are examined in this manifold. we obtain some properties of this manifold having the vectors mentioned above.

Hexagonal quasigroup is idempotent, medial and semisymmetric quasigroup. In this article we define and study vectors, sum of vectors and transfers. The main result is the theorem on isomorphism between the group of vectors, group of transfers and the Abelian group from the characterization theorem of the hexagonal quasigroups. 1. Hexagonal quasigroup Hexagonal quasigroups are defined in article...

This article presents some interesting properties about a new type of graph associated to a group, the G-graphs [4]. We show that many properties of a group can be seen on its associated G-graph and that many common graphs are G-graphs. We explain how to build efficiently some symmetric and semisymmetric graphs using the G-graphs. We establish a link beetwen Cayley graphs [1,2] and G-graphs.