Abstract
In this paper, we study a semigroup induced by the index morphism on finite trees. This index morphism classify the set of all finite trees under certain equivalence relation, and this classification forms a semigroup. We define the indexing α by a map from this semigroup into the family of all von Neumann algebras. Then the images of α become new von Neumann algebras containing their natural diagonal W*-subalgebras. For naturally determined conditional expectations with affiliation, the Watatani’s extended Jones index of each image of α is preserved by the elements of the semigroup.
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Communicated by Palle Jorgensen.
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Cho, I. Index Semigroup and Indexing on von Neumann Algebras. Complex Anal. Oper. Theory 8, 683–707 (2014). https://doi.org/10.1007/s11785-011-0208-4
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DOI: https://doi.org/10.1007/s11785-011-0208-4
Keywords
- Finite directed graphs
- Graph groupoids
- Graph von Neumann algebras
- Graph inclusions
- Graph-index
- Jones index
- Quasi-bases
- Watatani’s extended Jones index
- Index-morphism
- Index semigroups