For a locally compact group
G let L1(G,ωλ) be the weighted group algebra. We characterize elements
g ∈ L1(G,ωλ) for which the operator Tg(f) = f ∗ g(f ∈ L1(G,ωλ)) is compact We
conclude a result due to S. Sakai that if G is a locally compact non-compact
group, then 0 is the only compact element of L1(G,λ), and a result due to C.
Akemann that if G is a compact group, then every element of L1(G,λ) is
compact.