Supercommutative algebra


In mathematics, a supercommutative algebra is a superalgebra such that for any two homogeneous elements x, y we have
where |x| denotes the grade of the element and is 0 or 1 according to whether the grade is even or odd, respectively.
Equivalently, it is a superalgebra where the supercommutator
always vanishes. Algebraic structures which supercommute in the above sense are sometimes referred to as skew-commutative associative algebras to emphasize the anti-commutation, or, to emphasize the grading, graded-commutative or, if the supercommutativity is understood, simply commutative.
Any commutative algebra is a supercommutative algebra if given the trivial gradation. Grassmann algebras are the most common examples of nontrivial supercommutative algebras. The supercenter of any superalgebra is the set of elements that supercommute with all elements, and is a supercommutative algebra.
The even subalgebra of a supercommutative algebra is always a commutative algebra. That is, even elements always commute. Odd elements, on the other hand, always anticommute. That is,
for odd x and y. In particular, the square of any odd element x vanishes whenever 2 is invertible:
Thus a commutative superalgebra always contains nilpotent elements.
A Z-graded anticommutative algebra with the property that for every element x of odd grade is called an alternating algebra.