6 research outputs found
De Re Updates
In this paper, we propose a lightweight yet powerful dynamic epistemic logic
that captures not only the distinction between de dicto and de re knowledge but
also the distinction between de dicto and de re updates. The logic is based on
the dynamified version of an epistemic language extended with the assignment
operator borrowed from dynamic logic, following the work of Wang and Seligman
(Proc. AiML 2018). We obtain complete axiomatizations for the counterparts of
public announcement logic and event-model-based DEL based on new reduction
axioms taking care of the interactions between dynamics and assignments.Comment: In Proceedings TARK 2021, arXiv:2106.1088
Non-Rigid Designators in Epistemic and Temporal Free Description Logics (Extended Version)
Definite descriptions, such as 'the smallest planet in the Solar System',
have been recently recognised as semantically transparent devices for object
identification in knowledge representation formalisms. Along with individual
names, they have been introduced also in the context of description logic
languages, enriching the expressivity of standard nominal constructors.
Moreover, in the first-order modal logic literature, definite descriptions have
been widely investigated for their non-rigid behaviour, which allows them to
denote different objects at different states. In this direction, we introduce
epistemic and temporal extensions of standard description logics, with nominals
and the universal role, additionally equipped with definite descriptions
constructors. Regarding names and descriptions, in these languages we allow
for: possible lack of denotation, ensured by partial models, coming from free
logic semantics as a generalisation of the classical ones; and non-rigid
designation features, obtained by assigning to terms distinct values across
states, as opposed to the standard rigidity condition on individual
expressions. In the absence of the rigid designator assumption, we show that
the satisfiability problem for epistemic free description logics is
NExpTime-complete, while satisfiability for temporal free description logics
over linear time structures is undecidable
Free Quantified Epistemic Logics
The paper presents an epistemic logic with quantification over agents of knowledge and with a syntactical distinction between de re and de dicto occurrences of terms. Knowledge de dicto is characterized as `knowledge that', and
knowlegde de re as `knowledge of'. Transition semantics turns out to be an adequate tool to account for the distinctions introduced