202 research outputs found
The Varieties of Ought-implies-Can and Deontic STIT Logic
STIT logic is a prominent framework for the analysis of multi-agent choice-making. In the available deontic extensions of STIT, the principle of Ought-implies-Can (OiC) fulfills a central role. However, in the philosophical literature a variety of alternative
OiC interpretations have been proposed and discussed. This paper provides a modular framework for deontic STIT that accounts for a multitude of OiC readings. In particular, we discuss, compare, and formalize ten such readings. We provide sound and complete sequent-style calculi for all of the various STIT logics accommodating these OiC principles. We formally analyze the resulting logics and discuss how the different OiC principles are logically related. In particular, we propose an endorsement principle describing which OiC readings logically commit one to other OiC readings
Intuitionistic Non-Normal Modal Logics: A general framework
We define a family of intuitionistic non-normal modal logics; they can bee
seen as intuitionistic counterparts of classical ones. We first consider
monomodal logics, which contain only one between Necessity and Possibility. We
then consider the more important case of bimodal logics, which contain both
modal operators. In this case we define several interactions between Necessity
and Possibility of increasing strength, although weaker than duality. For all
logics we provide both a Hilbert axiomatisation and a cut-free sequent
calculus, on its basis we also prove their decidability. We then give a
semantic characterisation of our logics in terms of neighbourhood models. Our
semantic framework captures modularly not only our systems but also already
known intuitionistic non-normal modal logics such as Constructive K (CK) and
the propositional fragment of Wijesekera's Constructive Concurrent Dynamic
Logic.Comment: Preprin
Intuitionistic non-normal modal logics: A general framework
International audienceWe define a family of intuitionistic non-normal modal logics; they can be seen as intuitionistic counterparts of classical ones. We first consider monomodal logics, which contain only Necessity or Possibility. We then consider the more important case of bimodal logics, which contain both modal operators. In this case we define several interactions between Necessity and Possibility of increasing strength, although weaker than duality. We thereby obtain a lattice of 24 distinct bimodal logics. For all logics we provide both a Hilbert axiomatisation and a cut-free sequent calculus, on its basis we also prove their decidability. We then define a semantic characterisation of our logics in terms of neighbourhood models containing two distinct neighbourhood functions corresponding to the two modalities. Our semantic framework captures modularly not only our systems but also already known intuitionistic non-normal modal logics such as Constructive K (CK) and the propositional fragment of Wijesekera's Constructive Concurrent Dynamic Logic
Crisp bi-G\"{o}del modal logic and its paraconsistent expansion
In this paper, we provide a Hilbert-style axiomatisation for the crisp
bi-G\"{o}del modal logic \KbiG. We prove its completeness w.r.t.\ crisp
Kripke models where formulas at each state are evaluated over the standard
bi-G\"{o}del algebra on . We also consider a paraconsistent expansion of
\KbiG with a De Morgan negation which we dub \KGsquare. We devise a
Hilbert-style calculus for this logic and, as a~con\-se\-quence of
a~conservative translation from \KbiG to \KGsquare, prove its completeness
w.r.t.\ crisp Kripke models with two valuations over connected via
.
For these two logics, we establish that their decidability and validity are
-complete.
We also study the semantical properties of \KbiG and \KGsquare. In
particular, we show that Glivenko theorem holds only in finitely branching
frames. We also explore the classes of formulas that define the same classes of
frames both in (the classical modal logic) and the crisp G\"{o}del
modal logic \KG^c. We show that, among others, all Sahlqvist formulas and all
formulas where and are monotone, define the
same classes of frames in and \KG^c
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