Three types of subsets of PG(2, q2) of type (0, 1, 2, q + 1) are defined, namely CF -sets, K -sets and H -sets. These subsets may also be obtained as the intersection of the Hermitian curve H with Baer subpencils of lines with vertex not on H. It is shown that under the Bruck–Bose representation these subsets correspond to three-dimensional elliptic quadrics, quadratic cones and hyperbolic quad...

First we define relations between the v = (s2+s+1}(s+l) flags (point-line incident pairs) of a finite projective plane of order s. Two flags a =(p,i) and b =(p' ,l'), where p and p' are two points and l and l' are two lines of the projective plane, are defined to be first associates if either p = p' or l = l'; second associates if p # p', l # l' but either p is incident also with l' or p' is in...

Jensen formulates classes of notions of forcing in [1]. We take subproper among those. This class is wider than proper, may differ from semiproper of Shelah and is iterable under the revised countable support a la Donder according to [1]. We formulate a class of notion of forcing whose definition involves less parameters than Jensen’s subproper and show that it iterates under a type of revised ...

Proof. If T were not complete, there would a sentence ψ such that neither ψ and ¬ψ would follow from T . But then T ∪ {ψ} and T ∪ {¬ψ} would have infinite models. Since λ ≥ |L|, both would actually have models of cardinality λ by the theorems of Skolem and Löwenheim. But these cannot be isomorphic, because they are not elementarily equivalent, contradicting the λ-categoricity of T . Theorem 1.2...