We present a class of transitive BLT-sets that contains several known examples and at least one new example over the field with 41 elements with automorphism group Z21 : (Z2 × Z2). This example is sporadic in the sense that it does not fall into any of the known infinite families of BLT-sets.

We prove that the usual logic programming definition of transitive closure is correct under the answer set semantics, and investigate under what conditions it is correct under the completion semantics. That definition is allowed here to be combined with an arbitrary set of rules that may contain negation as failure, not merely with a set of facts. This work is motivated by applications to answe...

This paper forms part of the general development of the theory of quasigroup permutation representations. Here, the concept of sharp transitivity is extended from group actions to quasigroup actions. Examples of nontrivial sharply transitive sets of quasigroup actions are constructed. A general theorem shows that uniformity of the action is necessary for the existence of a sharply transitive se...

The group of projectivities of (a line of) a projective plane is always 3-transitive. It is well known that the projective planes with a sharply 3-transitive group of projectivities are classi/ed: they are precisely the Pappian projective planes. It is also well known that the group of projectivities of a generalized polygon is 2-transitive. Here, we classify all generalized quadrangles, all /n...