New blocking semiovals in with a large homology group

A blocking semioval in a projective plane is a set of points which is both a semioval and a blocking set. In this paper, blocking semiovals in the Desaguesian projective plane PG ( 2 , s 2 ) admitting an order s + 1 homology group are considered. By looking at the geometry of the orbits on points of such a group we find two new blocking semiovals of large size in PG ( 2 , 5 2 ) .