科研之友
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摘要
We give a new proof to a result due to T. Shimizu stating that for a locally compact group G and the associated group algebra L-1(G), if S is a measurable subset of G, then a necessary and sufficient condition for the subspace of all functions in L-1(G) that vanish almost everywhere off S to be an algebra is that S is equal to a subsemigroup of G, locally almost everywhere. Our proof bypasses a deep result of A. Ionescu Tulcea and C. Ionescu Tulcea, used in Shimizu's proof, and is for the most part functional analytic.
- 出版日期2014-2
