Published online by Cambridge University Press: 19 June 2017
Given a scattered space
$\mathfrak{X} = \left( {X,\tau } \right)$
and an ordinal λ, we define a topology
$\tau _{ + \lambda } $
in such a way that τ
+0 = τ and, when
$\mathfrak{X}$
is an ordinal with the initial segment topology, the resulting sequence {τ
+λ}λ∈Ord coincides with the family of topologies
$\left\{ {\mathcal{I}_\lambda } \right\}_{\lambda \in Ord} $
used by Icard, Joosten, and the second author to provide semantics for polymodal provability logics.
We prove that given any scattered space
$\mathfrak{X}$
of large-enough rank and any ordinal λ > 0, GL is strongly complete for τ
+
λ. The special case where
$\mathfrak{X} = \omega ^\omega + 1$
and λ = 1 yields a strengthening of a theorem of Abashidze and Blass.