EN
Let B be a complex topological unital algebra. The left joint spectrum of a set S ⊂ B is defined by the formula
$σ_l(S)$ = {$(λ(s))_{s∈ S} ∈ ℂ^S | {s-λ(s)}_{s∈S}$ generates a proper left ideal}$.
Using the Schur lemma and the Gelfand-Mazur theorem we prove that $σ_l(S)$ has the spectral mapping property for sets S of pairwise commuting elements if
(i) B is an m-convex algebra with all maximal left ideals closed, or
(ii) B is a locally convex Waelbroeck algebra.
The right ideal version of this result is also valid.