Английская Википедия:Alternativity
Шаблон:Short description Шаблон:Technical Шаблон:Distinguish In abstract algebra, alternativity is a property of a binary operation. A magma G is said to be Шаблон:Visible anchor if <math>(xx)y = x(xy)</math> for all <math>x, y \in G</math> and Шаблон:Visible anchor if <math>y(xx) = (yx)x</math> for all <math>x, y \in G.</math> A magma that is both left and right alternative is said to be Шаблон:Visible anchor (Шаблон:Visible anchor).[1]
Any associative magma (that is, a semigroup) is alternative. More generally, a magma in which every pair of elements generates an associative submagma must be alternative. The converse, however, is not true, in contrast to the situation in alternative algebras. In fact, an alternative magma need not even be power-associative: already the expression <math>(xx)(xx)</math> cannot be proven to be identical to expressions such as <math>(x(x(xx)))</math> purely by alternativity.
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