Some blocking semiovals of homology type in planes of square order

摘要

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. The geometry of the point-orbits of such a group is studied. Using this geometry two new blocking semiovals are constructed in PG(2, 5~2). Their automorphism group is also discussed.