On the algebraic decomposition of a centralizer algebra of the hyperoctahedral group
On the algebraic decomposition of a centralizer algebra of the hyperoctahedral group
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超八面体群的中心化代数的代数分解
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通讯作者:
R. Orellana
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作者:
R. Orellana
In this paper we give a combinatorial rule for the decomposition of tensor powers of the signed permutation representation of the hyperoctahedral group. We then use this rule to describe the Bratteli diagram of a centralizer algebra of this group over k-th tensor space. We show that a basis for this algebra can be described completely in terms of set partitions and we give a set of generators and relations. Introduction In [J] Jones has given a description of the centralizer algebra EndSn(V ) where V = C and Sn (symmetric group) acts by permutations on V and it acts diagonally on V . This algebra was independently introduced by Martin [Ma] and named the Partition algebra. The main motivation for studying the partition algebra is in generalizing the Temperley-Lieb algebras and the Potts model in statistical mechanics. A survey on the Partition algebra has been written by Halverson and Ram [HR]. The main objective of this paper is to study a family of subalgebras of the Partition algebra. In this paper we look at the corresponding centralizer algebras of the hyperoctahedral group. This group is the wreath product of the cyclic group of order 2 and the symmetric group, which we will denote by Gn := Z/2ZwrSn. Let V = C, then Gn acts on this vector space via signed permutations. The semisimple decomposition of the algebra EndGn(V ) can be obtained by decomposing the tensor product V ⊗k in terms of simple Gn-modules by the double centralizer theory. In this paper we prove the decomposition of the Gn-module V ⊗k in terms of irreducibles. Since the representations of Gn are indexed by ordered pairs of Young diagrams, we obtained an indexing set for the irreducible representations of EndGn(V ) in terms of ordered pairs of Young diagrams. This decomposition rule also yields a purely combinatorial rule in terms of pairs of Young diagrams for the restriction and induction of simple modules of this centralizer algebras. This branching rule allows us to write the Bratteli diagram of these centralizer algebras. 1991 Mathematics Subject Classification. Primary 16G99, 05E05; Secondary 20F55, 16S99.