*Wissenschaftliches Programm* † *Liste der Vortragenden*

Sektion 12
Donnerstag, 21.09.2000, 15.00–15.20 Uhr, WIL C 102

Circularity of certain F-pairs

Hubert Kiechle, Universitšt Hamburg

An F-pair (N, P) consists of two groups (N, +) and P such that P acts as an automorphism group on N, and such that for every f  (- P \ {1}, the map f - 1 : N --> N is bijective. We call (N, P) finite if N is finite. In this case the condition is equivalent to the condition that P acts fixed point free on N.

A finite F-pairs gives rise to the 2-designs (N, B) with the set B := {Pa + b; a, b  (- N, a /= 0}. The F-pair and the design are called circular if |B  /~\ B'| < 2 for all B, B'  (- B. We’ll present some new results on the circularity of F-pairs with non-abelian P.