2015/11/18 by Aguilera, Juan P., Fernández-Duque, David · 1 citation
#FOS: Mathematics #Logic (math.LO)
paper · doi:10.48550/arxiv.1511.05882
Abashidze and Blass independently proved that the modal logic \sfGL is complete for its topological interpretation over any ordinal greater than or equal to ωω equipped with the interval topology. Icard later introduced a family of topologies \mathcal Iλ for λ< ω, with the purpose of providing semantics for Japaridze's polymodal logic \sfGLP ω. Icard's construction was later extended by Joosten and the second author to arbitrary ordinals λ≥ ω. We further generalize Icard topologies in this article. Given a scattered space \mathfrak X = (X, τ) and an ordinal λ, we define a topology τ+λ in such a way that τ+0 is the original topology τ and τ+λ coincides with \mathcal Iλ when \mathfrak X is an ordinal endowed with the left topology. We then prove that, given any scattered space \mathfrak X and any ordinal λ>0 such that the rank of (X, τ) is large enough, \sfGL is strongly complete for τ+λ. One obtains the original Abashidze-Blass theorem as a consequence of the special case where \mathfrak X=ωω and λ=1.