We show that if a real hypersurface of a complex space form M2(c),c≠0 admits an almost gradient pseudo-Ricci soliton and satisfies Sξ=βξ for some function β, where S denotes the Ricci operator, then M is either a ruled real hypersurface or a Hopf hypersurface admitting a trivial gradient pseudo-Ricci soliton.

In this paper we present a method for computing the dihedral angle sums (and their two-sided estimates) of cartesian and skew product polytopes provided the sums of dihedral angles (or their estimates) are known for the factors. In addition, a formula for computing the number of facets of such product polytopes is derived. The method proposed is very universal and illustrated by several examples. The estimates are in a full agreement with known results for prisms and hexahedra.

A full classification (up to equivalence) of all minimal blocking sets in PG(2, 9) was obtained by computer. The resulting numbers of minimal blocking sets are tabulated according to size of the set and order of the automorphism group. For the minimal blocking sets with the larger automorphism groups explicit (geometric) descriptions are given. Some of these results can also be generalised to Desarguesian projective planes of higher order. We also give a complete list of all blocking semiovals in PG(2, 9) (up to equivalence).