ABSTRACT
The concept of a finite derivable affine plane was conceived by T.G. Ostrom in the early 1960's (see [61] and [62]) and has been arguably the most impor tant construction procedure of affine planes developed in the last thirty-five years. Certain finite affine planes may be ‘derived’ to produce other affine planes of the same order. For example, the Hall planes of order q2 originally constructed by Marshall Hall Jr. [26] by coordinate methods were shown by Albert [1] to be constructible from any Desarguesian affine plane of order q2 by the method of derivation. The Hughes planes [27] of order q2 were shown to be derivable and the projective planes constructed were the first examples of finite projective planes of Lenz-Barlotti class II-l (there is a single, incident, point-line transitivity). The planes obtained were indepen dently discovered by T.G. Ostrom [63] and L.A. Rosati [69] and are called the ‘Ostrom-Rosati planes’.
