A local Banach algebra 
is stably unital if the collection 
of square infinite-dimensional
matrices with entries in 
has an approximate identity
consisting of idempotents.
Stably Unital
See also
*-Algebra, Algebra, Analytic Function, Approximate Identity, Banach Algebra, Completion, Involution, Local Banach Algebra, Normed Space, Positive Element, Subalgebra, UnitalThis entry contributed by Christopher Stover
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References
Blackadar, B. K-Theory for Operator Algebras. New York: Cambridge University Press, 1998.Cite this as:
Stover, Christopher. "Stably Unital." From MathWorld--A Wolfram Web Resource, created by Eric W. Weisstein. https://mathworld.wolfram.com/StablyUnital.html