COMMUTANT

In algebra, the 'commutant' of a subset ''S'' of an semigroup (such as an algebra or a group) ''A'' over a field ''K'' is the subset ''S''′ of elements of ''A'' commuting with every element of ''S''. In other words,
:$S\text{'}=\{xin\; A:\; sx=xs\; mbox\{for\}\; mbox\{every\}\; sin\; S\}.$
''S''′ forms a subalgebra. This is analogous to the concept of a centralizer in group theory.

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See also

See also

★ Bicommutant

★ von Neumann bicommutant theorem