#### Vol. 15, No. 1, 1965

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A characterization of free projective planes

### Laurent Siebenmann

Vol. 15 (1965), No. 1, 293–298
##### Abstract

A characterization of free projective planes is given that is more symmetrical than the original definition of M. Hall. It tends to very simple proofs of two fundamental theorems due to M. Hall and L. I. Kopejkina-one being the result that every subplane of a free plane is free.

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