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An Upper Bound for the Length of a Finite-Dimensional Algebra

✍ 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.

✦ 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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