An Upper Bound for the Length of a Finite-Dimensional Algebra
β Scribed by Christopher J Pappacena
- Publisher
- Elsevier Science
- Year
- 1997
- Tongue
- English
- Weight
- 180 KB
- Volume
- 197
- Category
- Article
- ISSN
- 0021-8693
No coin nor oath required. For personal study only.
β¦ Synopsis
Let F be a field, and let A be a finite-dimensional F-algebra. Write d s dim A, F and let e be the largest degree of the minimal polynomial for any a g A. Define Ε½ .
' the function f d, e s e 2dr e y 1 q 1r4 q er2 y 2. We prove that, if S is Ε½ .
any finite generating set for A as an F-algebra, the words in S of length less than Ε½ . f d, e span A as an F-vector space. In the special case of n-by-n matrices, this
' bound becomes f n , n s n 2n r n y 1 q 1r4 q nr2 y 2 g O n . This is Ε½ .
Ε½ 2 . a substantial improvement over previous bounds, which have all been O n . We also prove that, for particular sets S of matrices, the bound can be sharpened to one that is linear in n. As an application of these results, we reprove a theorem of Small, Stafford, and Warfield about semiprime affine F-algebras.
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