arXiv subjects

Sonia Marin

Publications and source records attributed to Sonia Marin.

12 recordsLinked to original sources

arXiv2026

Intuitionistic Justification Logic, Semantically

Justification logics are explicit versions of modal logic. In the classical setting, this means boxes are refined with explicit proof terms and interact with each other through proof operations. This exercise was extended to intuitionistic modal logic with native diamonds. In this setting, diamonds are refined to satisfier terms and come equipped with additional operations. Justification logic enjoys a connection to its corresponding modal logic through a realisation theorem. In the classical setting, this is achieved through either proof-theoretic or semantic methodology. So far, intuitionistic justification logic with satisfiers has only been presented syntactically with a proof-theoretic realisation theorem. We present two classes of semantics for intuitionistic justification logic with soundness and completeness results: basic modular models, which extend possible world semantics for intuitionistic propositional logic; modular models which contain Kripke-style machinery to promote "backwards compatibility" to modal logic. Using modular models, we present a realisation theorem to establish a connection between intuitionistic justification logic and its corresponding intuitionistic modal logic.

cs.LO↗

arXiv2026

The proof theory and semantics of second-order (intuitionistic) tense logic

We develop a second-order extension of intuitionistic modal logic, allowing quantification over propositions, both syntactically and semantically. A key feature of second-order logic is its capacity to define positive connectives from the negative fragment. Duly we are able to recover the diamond (and its associated theory) using only boxes, as long as we include both forward and backward modalities (`tense' modalities). We propose axiomatic, proof theoretic and model theoretic definitions of `second-order intuitionistic tense logic', and ultimately prove that they all coincide. In particular we establish completeness of a labelled sequent calculus via a proof search argument, yielding at the same time a cut-admissibility result. Our methodology also applies to the classical version of second-order tense logic, which we develop in tandem with the intuitionistic case.

cs.LO↗

arXiv2025

Justification Logic for Intuitionistic Modal Logic (Extended Technical Report)

Justification logics are an explication of modal logic; boxes are replaced with proof terms formally through realisation theorems. This can be achieved syntactically using a cut-free proof system e.g. using sequent, hypersequent or nested sequent calculi. In constructive modal logic, boxes and diamonds are decoupled and not De Morgan dual. Kuznets, Marin and Straßburger provide a justification counterpart to constructive modal logic CK and some extensions by making diamonds explicit by introducing new terms called satisfiers. We continue the line of work to provide a justification counterpart to Fischer Servi's intuitionistic modal logic IK and its extensions with the t and 4 axioms. We: extend the syntax of proof terms to accommodate the additional axioms of intuitionistic modal logic; provide an axiomatisation of these justification logics; provide a syntactic realisation procedure using a cut-free nested sequent system for intuitionistic modal logic introduced by Straßburger.

cs.LO↗

arXiv2024

Nested Sequents for Quasi-transitive Modal Logics

Previous works by Goré, Postniece and Tiu have provided sound and cut-free complete proof systems for modal logics extended with path axioms using the formalism of nested sequent. Our aim is to provide (i) a constructive cut-elimination procedure and (ii) alternative modular formulations for these systems. We present our methodology to achieve these two goals on a subclass of path axioms, namely quasi-transitivity axioms.

cs.LO↗

arXiv2023

Intuitionistic Gödel-Löb logic, à la Simpson: labelled systems and birelational semantics

We derive an intuitionistic version of Gödel-Löb modal logic ($\sf{GL}$) in the style of Simpson, via proof theoretic techniques. We recover a labelled system, $\sf{\ell IGL}$, by restricting a non-wellfounded labelled system for $\sf{GL}$ to have only one formula on the right. The latter is obtained using techniques from cyclic proof theory, sidestepping the barrier that $\sf{GL}$'s usual frame condition (converse well-foundedness) is not first-order definable. While existing intuitionistic versions of $\sf{GL}$ are typically defined over only the box (and not the diamond), our presentation includes both modalities. Our main result is that $\sf{\ell IGL}$ coincides with a corresponding semantic condition in birelational semantics: the composition of the modal relation and the intuitionistic relation is conversely well-founded. We call the resulting logic $\sf{IGL}$. While the soundness direction is proved using standard ideas, the completeness direction is more complex and necessitates a detour through several intermediate characterisations of $\sf{IGL}$.

cs.LO↗

arXiv2023

A Logical Interpretation of Asynchronous Multiparty Compatibility

Session types are types for specifying the protocols that communicating processes must follow in a concurrent system. When composing two or more well-typed processes, a session typing system must check whether such processes are multiparty compatible, a property that guarantees that all sent messages are eventually received and no deadlock ever occurs. Previous work has shown that duality and the more general notion of coherence are sufficient syntactic conditions for guaranteeing the multiparty compatibility property. In this paper, following a propositions-as-types fashion which relates session types to linear logic, we generalise coherence to forwarders. Forwarders are processes that act as middleware by forwarding messages according to a given protocol. Our main result shows that forwarders not only generalise coherence, but fully capture all well-typed multiparty compatible processes.

cs.LO↗

arXiv2023

Intuitionistic S4 is decidable

In this paper we demonstrate decidability for the intuitionistic modal logic S4 first formulated by Fischer Servi. This solves a problem that has been open for almost thirty years since it had been posed in Simpson's PhD thesis in 1994. We obtain this result by performing proof search in a labelled deductive system that, instead of using only one binary relation on the labels, employs two: one corresponding to the accessibility relation of modal logic and the other corresponding to the order relation of intuitionistic Kripke frames. Our search algorithm outputs either a proof or a finite counter-model, thus, additionally establishing the finite model property for intuitionistic S4, which has been another long-standing open problem in the area.

cs.LO↗

arXiv2022

Separability and harmony in ecumenical systems

The quest of smoothly combining logics so that connectives from classical and intuitionistic logics can co-exist in peace has been a fascinating topic of research for decades now. In 2015, Dag Prawitz proposed a natural deduction system for an ecumenical first-order logic. We start this work by proposing a {\em pure} sequent calculus version for it, in the sense that connectives are introduced without the use of other connectives. For doing this, we extend sequents with an extra context, the stoup, and define the ecumenical notion of polarities. Finally, we smoothly extend these ideas for handling modalities, presenting pure labeled and nested systems for ecumenical modal logics.

cs.LO↗

arXiv2021

Forwarders as Process Compatibility, Logically

Session types define protocols that processes must follow when communicating. The special case of binary session types, i.e. type annotations of protocols between two parties, is known to be in a propositions-as-types correspondence with linear logic. In previous work, we have shown that the generalization to multiparty session types can be expressed either by coherence proofs or by arbiters, processes that act as middleware by forwarding messages according to the given protocol. In this paper, following the propositions-as-types fashion, we generalize arbiters to a logic, which we call forwarder logic, a fragment of classical linear logic still satisfying cut-elimination. Our main result is summarized as follows: forwarders generalize coherence and give an elegant proof-theoretic characterization of multiparty compatibility, a property of concurrent systems guaranteeing that all sent messages are eventually received and no deadlock ever occurs.

cs.PL↗

arXiv2021

Synchronous Forwarders

Session types are types for specifying protocols that processes must follow when communicating with each other. Session types are in a propositions-as-types correspondence with linear logic. Previous work has shown that a multiparty session type, a generalisation of session types to protocols of two or more parties, can be modelled as a proof of coherence, a generalisation of linear logic duality. And, protocols expressed as coherence can be simulated by arbiters, processes that act as a middleware by forwarding messages according to the given protocol. In this paper, we generalise the concept of arbiter to that of synchronous forwarder, that is a processes that implements the behaviour of an arbiter in several different ways. In a propositions-as-types fashion, synchronous forwarders form a logic equipped with cut elimination which is a special restriction of classical linear logic. Our main result shows that synchronous forwarders are a characterisation of coherence, i.e., coherence proofs can be transformed into synchronous forwarders and, viceversa, every synchronous forwarder corresponds to a coherence proofs.

cs.PL↗

arXiv2021

Focused Proof-search in the Logic of Bunched Implications

The logic of Bunched Implications (BI) freely combines additive and multiplicative connectives, including implications; however, despite its well-studied proof theory, proof-search in BI has always been a difficult problem. The focusing principle is a restriction of the proof-search space that can capture various goal-directed proof-search procedures. In this paper, we show that focused proof-search is complete for BI by first reformulating the traditional bunched sequent calculus using the simpler data-structure of nested sequents, following with a polarised and focused variant that we show is sound and complete via a cut-elimination argument. This establishes an operational semantics for focused proof-search in the logic of Bunched Implications.

cs.LO↗

arXiv2020

Ecumenical modal logic

The discussion about how to put together Gentzen's systems for classical and intuitionistic logic in a single unified system is back in fashion. Indeed, recently Prawitz and others have been discussing the so called Ecumenical Systems, where connectives from these logics can co-exist in peace. In Prawitz' system, the classical logician and the intuitionistic logician would share the universal quantifier, conjunction, negation, and the constant for the absurd, but they would each have their own existential quantifier, disjunction, and implication, with different meanings. Prawitz' main idea is that these different meanings are given by a semantical framework that can be accepted by both parties. In a recent work, Ecumenical sequent calculi and a nested system were presented, and some very interesting proof theoretical properties of the systems were established. In this work we extend Prawitz' Ecumenical idea to alethic K-modalities.

cs.LO↗