A Characterization of Compact Groups

David L. Johnson
1979 Proceedings of the American Mathematical Society  
It is shown that the group algebra L\G) of a locally compact group G is an ideal in the bidual Ll(G)** of Ll(G) (equipped with Arens product) if and only if G is compact.
doi:10.2307/2043169 fatcat:proqfwfao5foxacc4qarkgnzia