The collineation groups of even order translation planes which are cubic extensions of flag-transitive planes are determined. 2000 Mathematics Subject Classification. Primary 51E.

We establish the connections between finite projective planes admitting a collineation group of Lenz–Barlotti type I.3 or I.4, partially transitive planes of type (3) in the sense of Hughes, and planes admitting a quasiregular collineation group of type (g) in the Dembowski– Piper classification; our main tool is an equivalent description by a certain type of di¤erence set relative to disjoint ...