Schur's lemma

Quillen's lemma

Let 𝐴 be a 𝕂-monoid over 𝕂 and 𝑉 be a simple 𝐴-module. If 𝐴 has a filtration {𝐹𝑖𝐴}βˆžπ‘–=1 such that 1 ∈𝐹0𝐴 and the associated graded algebra is a finitely-generated commutative 𝕂-algebra, then every 𝐴-module endomorphism πœ— βˆˆπ΄π–¬π—ˆπ–½(𝑉,𝑉) is an algebraic element over 𝕂.1 #m/thm/module

Proof

#missing/proof

Corollaries

The following algebras fulfil the hypothesis:

  1. The Universal enveloping algebra of a finite-dimensional Lie algebra, since by PoincarΓ©-Birkhoff-Witt theorem πΊβˆ™π‘ˆ(𝔀) =π‘†βˆ™π”€.


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Footnotes

  1. 1969. On the endomorphism ring of a simple module over an enveloping algebra, p. 171 ↩