Reworking on affine exterior algebra of Grassmann: Peano and his School

In this paper a construction of affine exterior algebra of Grassmann, with a special attention to the revisitation of this subject operated by Peano and his School, is examined from a historical viewpoint. Even if the exterior algebra over a vector space is a well known concept, the construction of an exterior algebra over an affine space, in which points and vectors coexist, has been neglected. This paper wants to fill this lack. Some attention is given to the introduction of defining by abstraction (today called definition by quotienting or by equivalence relation), a procedure due to and used by Peano to define geometric forms, basic elements of an affine exterior algebra. This Peano’s innovative way of defining, is a relevant contribution to mathematics. It is observed that in the construction of an affine exterior algebra on the Euclidean three-dimensional space, Grassmann and Peano make use of metric concepts: an accurate analysis shows that, in some cases, the metric aspects can be eliminated, putting into evidence the sufficiency of the underlying affine structure of the Euclidean space. In the final part of the paper some geometrical and mechanical applications and interpretations of the affine exterior algebra given by Grassmann and Peano are presented.