Questions concerning matrix algebras and invariance of spectrum
LetA andB be unital Banach algebras withA a subalgebra ofB. Denote the algebra of alln xn matrices with entries fromA byMn (A). In this paper we prove some results concerning the open question: IfA is inverse closed inB, then isMn (A) inverse closed inMn (B)? We also study related questions in the setting where A is a symmetric Banach *-algebra.
Volume 129 | Issue 5
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