The centralizer of a Cartan subalgebra of a Jordan algebra

Author:
Edgar G. Goodaire

Journal:
Trans. Amer. Math. Soc. **235** (1978), 314-322

MSC:
Primary 16A64; Secondary 17C25, 17C10

MathSciNet review:
0460384

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Abstract: If *L* is a diagonable subspace of an associative algebra *A* over a field is spanned by commuting elements and the linear transformations ad , are simultaneously diagonalizable), then a map is said to be a weight of *L* on an *A*-module *V* if the space is nonzero. It is shown that if *A* is finite dimensional semisimple and the characteristic of is zero then the centralizer of *L* in *A* is the centralizer of an element if and only if *x* distinguishes the weights of *L* on every irreducible *A*-module. This theorem can be used to show that for each representative *V* of an isomorphism class of irreducible *A*-modules and for each weight of *L* on *V*, the centralizer of *L* contains the matrix ring and in fact is the direct sum of all such algebras. If *J* is a finite dimensional simple reduced Jordan algebra, one can determine precisely those *x* in *J* whose centralizer in the universal enveloping algebra of *J* coincides with the centralizer of a Cartan subalgebra. The simple components of such a centralizer can also be found and in fact are listed for the degree case.

**[1]**Edgar G. Goodaire,*Irreducible representations of algebras*, Canad. J. Math.**26**(1974), 1118–1129. MR**0349763****[2]**Edgar G. Goodaire,*A classification of Jordan bimodules by weights*, Comm. Algebra**6**(1978), no. 9, 887–910. MR**0470005****[3]**Nathan Jacobson,*Structure and representations of Jordan algebras*, American Mathematical Society Colloquium Publications, Vol. XXXIX, American Mathematical Society, Providence, R.I., 1968. MR**0251099**

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DOI:
https://doi.org/10.1090/S0002-9947-1978-0460384-8

Keywords:
Diagonable subspace,
weighted representation,
reduced Jordan algebra,
Cartan subalgebra,
universal enveloping algebra

Article copyright:
© Copyright 1978
American Mathematical Society