A characterization of linear-multiplicative functionals in topological algebras

The classical Gleason–Kahane–Żelazko theorem for complex Banach algebras was generalized for not necessary linear functionals by Kowalski and Słodkowski. We prove a version of the Kowalski–Słodkowski theorem for real Banach algebras and also for real and complex $A$-pseudoconvex algebras.