Fragment Of Intuitionistic Logic Research Articles

Finite axiomatizability of logics of distributive lattices with negation

Abstract This paper focuses on order-preserving logics defined from varieties of distributive lattices with negation, and in particular on the problem of whether these can be axiomatized by means Hilbert-style calculi that are finite (i.e. that contain a finite number of finitary rule schemata). On the negative side, we provide a syntactic condition on the equational presentation of a variety that entails failure of finite axiomatizability for the corresponding logic. An application of this result is that the logic of all distributive lattices with negation is not finitely axiomatizable; we likewise establish that the order-preserving logic of the variety of all Ockham algebras is also not finitely axiomatizable. On the positive side, we show that an arbitrary subvariety of semi-De Morgan algebras is axiomatized by a finite number of equations if and only if the corresponding order-preserving logic is axiomatized by a finite Hilbert-style calculus. This equivalence also holds for every subvariety of a Berman variety of Ockham algebras. We obtain, as a corollary, a new proof that the implication-free fragment of intuitionistic logic is finitely axiomatizable, as well as a new corresponding Hilbert-style calculus. Our proofs are constructive in that they allow us to effectively convert an equational presentation of a variety of algebras into a Hilbert-style calculus for the corresponding order-preserving logic, and vice versa. We also consider the assertional logics associated to the above-mentioned varieties, showing in particular that the assertional logics of finitely axiomatizable subvarieties of semi-De Morgan algebras are finitely axiomatizable as well.

A Calculus of Tracking: Theory and Practice

Abstract Online tracking techniques, the interactions among trackers, and the economic and social impact of these procedures in the advertising ecosystem have received increasing attention in the last years. This work proposes a novel formal model that describes the foundations on which the visible process of data sharing behaves in terms of the network configurations of the Internet (included CDNs, shared cookies, etc.). From our model, we define relations that can be used to evaluate the impact of different privacy mitigations and determine if websites should comply with privacy regulations. We show that the calculus, based on a fragment of intuitionistic logic, is tractable and constructive: any formal derivation in the model corresponds to an actual tracking practice that can be implemented given the current configuration of the Internet. We apply our model on a dataset obtained from OpenWPM to evaluate the effectiveness of tracking mitigations up to Alexa Top 100.

The complexity of disjunction in intuitionistic logic

AbstractWe study procedures for the derivability problem of fragments of intuitionistic logic. Intuitionistic logic is known to be PSPACE-complete, with implication being one of the main contributors to this complexity. In fact, with just implication alone, we still have a PSPACE-complete logic. We study fragments of intuitionistic logic with restricted implication and develop algorithms for these fragments which are based on the proof rules. We identify a core fragment whose derivability is solvable in linear time. Adding disjunction elimination to this core gives a logic which is solvable in co-NP. These sub-procedures are applicable to a wide variety of logics with rules of a similar flavour. We also show that we cannot do better than co-NP whenever disjunction elimination interacts with other rules.

Monotonic Distributive Semilattices

In the study of algebras related to non-classical logics, (distributive) semilattices are always present in the background. For example, the algebraic semantic of the {→, ∧, ⊤}-fragment of intuitionistic logic is the variety of implicative meet-semilattices (Chellas 1980; Hansen 2003). In this paper we introduce and study the class of distributive meet-semilattices endowed with a monotonic modal operator m. We study the representation theory of these algebras using the theory of canonical extensions and we give a topological duality for them. Also, we show how our new duality extends to some particular subclasses.

Intersection Type Systems and Logics Related to the Meyer–Routley System B+

Some, but not all, closed terms of the lambda calculus have types; these types are exactly the theorems of intuitionistic implicational logic. An extension of these simple (→) types to intersection (or →∧) types allows all closed lambda terms to have types. The corresponding →∧ logic, related to the Meyer–Routley minimal logic B+ (without ∨), is weaker than the →∧ fragment of intuitionistic logic. In this paper we provide an introduction to the above work and also determine the →∧ logics that correspond to certain interesting subsystems of the full →∧ type theory.

On a fragment of intuitionistic logic which is complete with respect to the kripke frames with finite domains

On a fragment of intuitionistic logic which is complete with respect to the kripke frames with finite domains

Concurrent programming as proof net construction

We propose a concurrent process calculus, called Calcul Parallèle Logique (CPL), based on the paradigm of computation as proof net construction in linear logic. CPL uses a fragment of first-order intuitionistic linear logic where formulas represent processes and proof nets represent successful computations. In these computations, communication is expressed in an asynchronous way by means of axiom links. We define testing equivalences for processes, which are based on a concept of interface, and use the power of proof theory in linear logic.

Propositional quantification in the monadic fragment of intuitionistic logic

AbstractWe study the monadic fragment of second order intuitionistic propositional logic in the language containing the standard propositional connectives and propositional quantifiers. It is proved that under the topological interpretation over any dense-in-itself metric space, the considered fragment collapses to Heyting calculus. Moreover, we prove that the topological interpretation over any dense-in-itself metric space of fragment in question coincides with the so-called Pitts' interpretation. We also prove that all the nonstandard propositional operators of the form q ↦ ∃p (q ↔ F(p)), where F is an arbitrary monadic formula of the variable p, are definable in the language of Heyting calculus under the topological interpretation of intuitionistic logic over sufficiently regular spaces.

On Proof Terms and Embeddings of Classical Substructural Logics

There is an intimate connection between proofs of the natural deduction systems and typed lambda calculus. It is well-known that in simply typed lambda calculus, the notion of formulae-as-types makes it possible to find fine structure of the implicational fragment of intuitionistic logic, i.e., relevant logic, BCK-logic and linear logic. In this paper, we investigate three classical substructural logics (GL, GLc, GLw) of Gentzen's sequent calculus consisting of implication and negation, which contain some of the right structural rules. In terms of Parigot's λμ-calculus with proper restrictions, we introduce a proof term assignment to these classical substructural logics. According to these notions, we can classify the λμ-terms into four categories. It is proved that well-typed GLx-λμ-terms correspond to GLx proofs, and that a GLx-λμ-term has a principal type if stratified where x is nil, c, w or cw. Moreover, we investigate embeddings of classical substructural logics into the corresponding intuitionistic substructural logics. It is proved that the Godel-style translations of GLx-λμ-terms are embeddings preserving substructural logics. As by-products, it is obtained that an inhabitation problem is decidable and well-typed GLx-λμ-terms are strongly normalizable.

The "Relevance" of Intersection and Union Types

The aim of this paper is to investigate a Curry-Howard interpre- tation of the intersection and union type inference system for Combinatory Logic. Types are interpreted as formulas of a Hilbert-style logic L, which turns out to be an extension of the intuitionistic logic with respect to provable dis- junctive formulas (because of new equivalence relations on formulas), while the implicational-conjunctive fragment of L is still a fragment of intuitionistic logic. Moreover, typable terms are translated in a typed version, so that ∨-∧- typed combinatory logic terms are proved to completely codify the associated logical proofs.

The undecidability of simultaneous rigid E-unification

Simultaneous rigid E-unification was introduced in 1987 by Gallier, Raatz and Snyder. It is used in the area of automated reasoning with equality in extension procedures, like the tableau method or the connection method. Many articles in this area assumed the existence of an algorithm for the simultaneous rigid E-unification problem. There were several faulty proofs of the decidability of this problem. In this paper we prove that simultaneous rigid E-unification is undecidable. As a consequence, we obtain the undecidability of the ℶ∗-fragment of intuitionistic logic with equality.

On fragments of Medvedev's logic

Medvedev's intermediate logic (MV) can be defined by means of Kripke semantics as the family of Kripke frames given by finite Boolean algebras without units as partially ordered sets. The aim of this paper is to present a proof of the theorem: For every set of connectivesΦ such that\(\{ \to , \vee , \urcorner \} \not \subseteq \Phi \subseteq \{ \to , \wedge , \urcorner \} \) theΦ-fragment ofMV equals theΦ fragment of intuitionistic logic. The final part of the paper brings the negative solution to the problem set forth by T. Hosoi and H. Ono, namely: is an intermediate logic based on the axiom (⌝a→b∨c) →(⌉a→b)∨(⌝a → c) separable?