EN
We investigate the weak spectral mapping property (WSMP)
$\overline{μ̂(σ(A))} = σ(μ̂(A))$,
where A is the generator of a 𝓒₀-semigroup in a Banach space X, μ is a measure, and μ̂(A) is defined by the Phillips functional calculus. We consider the special case when X is a Banach algebra and the operators $e^{At}$, t ≥ 0, are multipliers.