97 research outputs found
Coalgebraic completeness-via-canonicity for distributive substructural logics
We prove strong completeness of a range of substructural logics with respect
to a natural poset-based relational semantics using a coalgebraic version of
completeness-via-canonicity. By formalizing the problem in the language of
coalgebraic logics, we develop a modular theory which covers a wide variety of
different logics under a single framework, and lends itself to further
extensions. Moreover, we believe that the coalgebraic framework provides a
systematic and principled way to study the relationship between resource models
on the semantics side, and substructural logics on the syntactic side.Comment: 36 page
Principles and Implementation of Deductive Parsing
We present a system for generating parsers based directly on the metaphor of
parsing as deduction. Parsing algorithms can be represented directly as
deduction systems, and a single deduction engine can interpret such deduction
systems so as to implement the corresponding parser. The method generalizes
easily to parsers for augmented phrase structure formalisms, such as
definite-clause grammars and other logic grammar formalisms, and has been used
for rapid prototyping of parsing algorithms for a variety of formalisms
including variants of tree-adjoining grammars, categorial grammars, and
lexicalized context-free grammars.Comment: 69 pages, includes full Prolog cod
The ubiquity of conservative translations
We study the notion of conservative translation between logics introduced by
Feitosa and D'Ottaviano. We show that classical propositional logic (CPC) is
universal in the sense that every finitary consequence relation over a
countable set of formulas can be conservatively translated into CPC. The
translation is computable if the consequence relation is decidable. More
generally, we show that one can take instead of CPC a broad class of logics
(extensions of a certain fragment of full Lambek calculus FL) including most
nonclassical logics studied in the literature, hence in a sense, (almost) any
two reasonable deductive systems can be conservatively translated into each
other. We also provide some counterexamples, in particular the paraconsistent
logic LP is not universal.Comment: 15 pages; to appear in Review of Symbolic Logi
Towards Theory and Applications of Generalized Categories to Areas of Type Theory and Categorical Logic
Motivated by potential applications to theoretical computer science, in particular those areas where the Curry-Howard correspondence plays an important role, as well as by the ongoing search in pure mathematics for feasible approaches to higher category theory, we undertake a detailed study of a new mathematical abstraction, the generalized category. It is a partially defined monoid equipped with endomorphism maps defining sources and targets on arbitrary elements, possibly allowing a proximal behavior with respect to composition. We first present a formal introduction to the theory of generalized categories. We describe functors, equivalences, natural transformations, adjoints, and limits in the generalized setting. Next we indicate how the theory of monads extends to generalized categories, and discuss applications to computer science. In particular we discuss implications for the functional programming paradigm, and discuss how to extend categorical semantics to the generalized setting. Next, we present a variant of the calculus of deductive systems developed in the work of Lambek, and give a generalization of the Curry-Howard-Lambek theorem giving an equivalence between the category of typed lambda-calculi and the category of cartesian closed categories and exponential-preserving morphisms that leverages the theory of generalized categories. Next, we develop elementary topos theory in the generalized setting of ideal toposes, by building upon the formalism we have previously developed for the extension of the Curry-Howard-Lambek theorem. In particular, we prove that ideal toposes possess the same Heyting algebra structure and squares of adjoints that ordinary toposes do. Finally, we develop generalized sheaves, and show that such categories form ideal toposes. We extend Lawvere and Tierney\u27s theorem relating j-sheaves and sheaves in the sense of Grothendieck to the generalized setting
BV and Pomset Logic Are Not the Same
BV and pomset logic are two logics that both conservatively extend unit-free multiplicative linear logic by a third binary connective, which (i) is non-commutative, (ii) is self-dual, and (iii) lies between the "par" and the "tensor". It was conjectured early on (more than 20 years ago), that these two logics, that share the same language, that both admit cut elimination, and whose connectives have essentially the same properties, are in fact the same. In this paper we show that this is not the case. We present a formula that is provable in pomset logic but not in BV
Sequents and link graphs: contraction criteria for refinements of multiplicative linear logic
In this thesis we investigate certain structural refinements of multiplicative linear logic, obtained by removing
structural rules like commutativity and associativity, in addition to the removal of weakening and contraction,
which characterizes linear logic. We define a notion of sequent that is able to capture these subtle structural
distinctions. For each of our calculi (MLL, NCLL, CNL, and NLR) we introduce a theory of two-sided
proof structures, which, in many respects, turns out to be more appropriate than the standard one-sided
approach. We prove correctness criteria, stating which among those proof structures correspond to proofs, i.e.
are proof nets. For this we introduce a contraction relation defined on the space of link graphs, a notion
sufficiently general to capture both proof structures and sequents, and the key-concept in this work, which is a
step towards a unification of the logical core of many distinct calculi
A universe of processes and some of its guises
Our starting point is a particular `canvas' aimed to `draw' theories of
physics, which has symmetric monoidal categories as its mathematical backbone.
In this paper we consider the conceptual foundations for this canvas, and how
these can then be converted into mathematical structure. With very little
structural effort (i.e. in very abstract terms) and in a very short time span
the categorical quantum mechanics (CQM) research program has reproduced a
surprisingly large fragment of quantum theory. It also provides new insights
both in quantum foundations and in quantum information, and has even resulted
in automated reasoning software called `quantomatic' which exploits the
deductive power of CQM. In this paper we complement the available material by
not requiring prior knowledge of category theory, and by pointing at
connections to previous and current developments in the foundations of physics.
This research program is also in close synergy with developments elsewhere, for
example in representation theory, quantum algebra, knot theory, topological
quantum field theory and several other areas.Comment: Invited chapter in: "Deep Beauty: Understanding the Quantum World
through Mathematical Innovation", H. Halvorson, ed., Cambridge University
Press, forthcoming. (as usual, many pictures
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