LEVELS AND SUBLEVELS OF QUATERNION ALGEBRAS
Author(s) -
Detlev W. Hoffmann
Publication year - 2010
Publication title -
mathematical proceedings of the royal irish academy
Language(s) - English
Resource type - Journals
eISSN - 2009-0021
pISSN - 1393-7197
DOI - 10.3318/pria.2010.110.1.95
Subject(s) - quaternion , mathematics , integer (computer science) , quaternion algebra , division (mathematics) , algebra over a field , division algebra , ring (chemistry) , pure mathematics , division ring , combinatorics , arithmetic , algebra representation , geometry , computer science , chemistry , organic chemistry , programming language
The level s (resp. sublevel s) of a ring R with 1 6= 0 is the smallest positive integer such that −1 (resp. 0) can be written as a sum of s (resp. s+1) nonzero squares in R, provided −1 (resp. 0) is a sum of nonzero squares at all. D.W. Lewis showed that any value of type 2n or 2n +1 can be realized as level of a quaternion division algebra, and in all these examples, the sublevel was 2n, which prompted the question whether or not the level and sublevel of a quaternion division algebra will always differ at most by one. In this note, we give a positive answer to that question.
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