We consider the problem of classifying (possibly non-commutative) .R-algebras of low rank over an arbitrary base ring R. We first classify algebras by their degree, and we relate the class of algebras of degree 2 to algebras with a standard involution. We then investigate a class of exceptional rings of degree 2 which occur in every rank n ≥ 1 and show that they essentially characterize all algebras of degree 2 and rank 3.
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