2 research outputs found
Knowledge and ignorance in Belnap--Dunn logic
In this paper, we argue that the usual approach to modelling knowledge and
belief with the necessity modality does not produce intuitive outcomes
in the framework of the Belnap--Dunn logic (, alias
-- first-degree entailment). We then motivate and introduce a non\-standard
modality that formalises knowledge and belief in
and use to define and that
formalise the \emph{unknown truth} and ignorance as \emph{not knowing whether},
respectively. Moreover, we introduce another modality that stands
for \emph{factive ignorance} and show its connection with .
We equip these modalities with Kripke-frame-based semantics and construct a
sound and complete analytic cut system for and
-- the expansions of with
and . In addition, we show that as it is customarily defined
in cannot define any of the introduced modalities, nor,
conversely, neither nor can define . We also
demonstrate that and are not interdefinable and
establish the definability of several important classes of frames using
Non-contingency in a Paraconsistent Setting
International audienceAbstract We study an extension of first-degree entailment (FDE) by Dunn and Belnap with a non-contingency operator which is construed as ‘ has the same value in all accessible states’ or ‘all sources give the same information on the truth value of ’. We equip this logic dubbed with frame semantics and show how the bi-valued models can be interpreted as interconnected networks of Belnapian databases with the operator modelling search for inconsistencies in the provided information. We construct an analytic cut system for the logic and show its soundness and completeness. We prove that is not definable via the necessity modality of . Furthermore, we prove that in contrast to the classical non-contingency logic, reflexive, and (among others) frames are definable