Walter Rudin

Homogeneity Problems in the Theory of Čech Compactifications

If X is a completely regular topological space, there exists a space sX, the so-called Cech compactification of X, which is characterized by the following three properties: sX is a compact (bicompact, in the older terminology) Hausdorff space, X is a dense subset of sX, and every bounded continuous real-valued function on X can be extended to a continuous function on βX [1; 831].

Idempotents in group rings

Abstract : The group generated by the support of an idempotent in a group ring is studied, both in the purely algebraic case and in the case of the group ring over a Banach Algebra. Under some conditions, this support group must be finite or even trivial. Under other conditions, there exist idempotents with infinite support or infinite support groups. (Author)