639 research outputs found
A simple sequent calculus for nominal logic
Nominal logic is a variant of first-order logic that provides support for
reasoning about bound names in abstract syntax. A key feature of nominal logic
is the new-quantifier, which quantifies over fresh names (names not appearing
in any values considered so far). Previous attempts have been made to develop
convenient rules for reasoning with the new-quantifier, but we argue that none
of these attempts is completely satisfactory.
In this article we develop a new sequent calculus for nominal logic in which
the rules for the new- quantifier are much simpler than in previous attempts.
We also prove several structural and metatheoretic properties, including
cut-elimination, consistency, and equivalence to Pitts' axiomatization of
nominal logic
Failure of interpolation in the intuitionistic logic of constant domains
This paper shows that the interpolation theorem fails in the intuitionistic
logic of constant domains. This result refutes two previously published claims
that the interpolation property holds.Comment: 13 pages, 0 figures. Overlaps with arXiv 1202.1195 removed, the text
thouroughly reworked in terms of notation and style, historical notes as well
as some other minor details adde
Failure of interpolation in the intuitionistic logic of constant domains
This paper shows that the interpolation theorem fails in the intuitionistic
logic of constant domains. This result refutes two previously published claims
that the interpolation property holds.Comment: 13 pages, 0 figures. Overlaps with arXiv 1202.1195 removed, the text
thouroughly reworked in terms of notation and style, historical notes as well
as some other minor details adde
Hypersequents and the Proof Theory of Intuitionistic Fuzzy Logic
Takeuti and Titani have introduced and investigated a logic they called
intuitionistic fuzzy logic. This logic is characterized as the first-order
Goedel logic based on the truth value set [0,1]. The logic is known to be
axiomatizable, but no deduction system amenable to proof-theoretic, and hence,
computational treatment, has been known. Such a system is presented here, based
on previous work on hypersequent calculi for propositional Goedel logics by
Avron. It is shown that the system is sound and complete, and allows
cut-elimination. A question by Takano regarding the eliminability of the
Takeuti-Titani density rule is answered affirmatively.Comment: v.2: 15 pages. Final version. (v.1: 15 pages. To appear in Computer
Science Logic 2000 Proceedings.
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
Hybrid Languages and Temporal Logic
Hybridization is a method invented by Arthur Prior for extending the expressive power of modal languages. Although developed in interesting ways by Robert Bull, and by the Sofia school (notably, George Gargov, Valentin Goranko, Solomon Passy and Tinko Tinchev) the method remains little known. In our view this has deprived temporal logic of a valuable tool.
The aim of the paper is to explain why hybridization is useful in temporal logic. We make two major points, the first technical, the second conceptual. First, we show that hybridization gives rise to well-behaved logics that exhibit an interesting synergy between modal and classical ideas. This synergy, obvious for hybrid languages with full first-order expressive strength, is demonstrated for a weaker local language capable of defining the Until operator, we provide a minimal axiomatization, and show that in a wide range of temporally interesting cases extended completeness results can be obtained automatically. Second, we argue that the idea of sorted atomic symbols which underpins the hybrid enterprise can be developed further. To illustrate this, we discuss the advantages and disadvantages of a simple hybrid language which can quantify over paths
Free Higher-Order Logic - Notion, Definition and Embedding in HOL
Free logics are a family of logics that are free of any existential assumptions. This family can roughly be divided into positive, negative, neutral and supervaluational free logic whose semantics differ in the way how nondenoting terms are treated. While there has been remarkable work done concerning the definition of free first-order logic, free higher-order logic has not been addressed thoroughly so far. The purpose of this thesis is, firstly, to give a notion and definition of free higher-order logic based on simple type theory and, secondly, to propose faithful shallow semantical embeddings of free higher-order logic into classical higher order logic found on this definition. Such embeddings can then effectively be utilized to enable the application of powerful state-of-the-art higher-order interactive and automated theorem provers for the formalization and verification and also the further development of increasingly important free logical theories
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