Significance of The Regular Representation of A Group
To say that G acts on itself by multiplication is tautological. If we consider this action as a permutation representation it is characterised as having a single orbit and stabilizer the identity subgroup {e} of G. The regular representation of G, for a given field K, is the linear representation made by taking this permutation representation as a set of basis vectors of a vector space over K. The significance is that while the permutation representation doesn't decompose - it is transitive - the regular representation in general breaks up into smaller representations. For example if G is a finite group and K is the complex number field, the regular representation decomposes as a direct sum of irreducible representations, with each irreducible representation appearing in the decomposition with multiplicity its dimension. The number of these irreducibles is equal to the number of conjugacy classes of G.
The article on group algebras articulates the regular representation for finite groups, as well as showing how the regular representation can be taken to be a module.
Read more about this topic: Regular Representation
Famous quotes containing the words significance of, significance, regular and/or group:
“To grasp the full significance of life is the actor’s duty, to interpret it is his problem, and to express it his dedication.”
—Marlon Brando (b. 1924)
“The hypothesis I wish to advance is that ... the language of morality is in ... grave disorder.... What we possess, if this is true, are the fragments of a conceptual scheme, parts of which now lack those contexts from which their significance derived. We possess indeed simulacra of morality, we continue to use many of the key expressions. But we have—very largely if not entirely—lost our comprehension, both theoretical and practical, of morality.”
—Alasdair Chalmers MacIntyre (b. 1929)
“They were regular in being gay, they learned little things that are things in being gay, they learned many little things that are things in being gay, they were gay every day, they were regular, they were gay, they were gay the same length of time every day, they were gay, they were quite regularly gay.”
—Gertrude Stein (1874–1946)
“We often overestimate the influence of a peer group on our teenager. While the peer group is most influential in matters of taste and preference, we parents are most influential in more abiding matters of standards, beliefs, and values.”
—David Elkind (20th century)