Elaine Pimentel

Victor Barroso-Nascimento, Maria Osório, Elaine Pimentel

Logical bilateralism challenges traditional concepts of logic by treating assertion and denial as independent yet opposed acts. While initially devised to justify classical logic, its constructive variants show that both acts admit intuitionistic interpretations. This paper presents a bilateral system where a formula cannot be both provable and refutable without contradiction, offering a framework for modelling epistemic entities, such as mathematical proofs and refutations, that exclude inconsistency. The logic is formalised through a bilateral natural deduction system with desirable proof-theoretic properties, including normalisation. We also introduce a base-extension semantics requiring explicit constructions of proofs and refutations while preventing them from being established for the same formula. The semantics is proven sound and complete with respect to the calculus. Finally, we show that our notion of refutation corresponds to David Nelson's constructive falsity, extending rather than revising intuitionistic logic and reinforcing the system's suitability for representing constructive epistemic reasoning.

Luiz Carlos Pereira, Victor Barroso-Nascimento, Elaine Pimentel

In this paper, we revisit Glivenko's theorems, foundational results relating classical and intuitionistic logic, from an ecumenical perspective. We begin by discussing the historical context and significance of Glivenko's original contributions, and then examine their extensions and reinterpretations within ecumenical logical frameworks. Our analysis focuses on three ecumenical systems: Prawitz's natural deduction system NE; the system NEK, closely related to one introduced by Krauss in an unpublished manuscript; and the ECI system proposed by Barroso-Nascimento.

Renato R. Leme, Carlos Olarte, Elaine Pimentel

Restricted non-deterministic matrices (RNmatrices) impose constraints on the rows of non-deterministic matrices (Nmatrices), filtering out ``unsound" rows and retaining only ``valid" ones. This yields a more expressive framework than standard Nmatrices. Although this approach enables sound and complete semantics for a broad class of logics, \eg, paraconsistent logics, propositional intuitionistic logic, and the fifteen normal modal logics of the modal cube, no {\em efficient} decision procedures based on these semantics have been proposed. In this paper, we implement the RNmatrix framework to develop a new suite of automated theorem provers for these logics. By encoding RNmatrices and their elimination criteria as Satisfiability Modulo Theories (SMT) problems, we leverage SMT solvers to decide formula validity and construct countermodels. We illustrate the method for paraconsistent logics, where our prover outperforms the current state-of-the-art and provides the first implementation for the entire $C_n$ hierarchy, as well as for intuitionistic and modal logics, where our general-purpose prover achieves competitive performance.

Elaine Pimentel, Enrico Tassi

Logical frameworks and meta-languages form a common substrate for representing, implementing and reasoning about a wide variety of deductive systems of interest in logic and computer science. Their design, implementation and their use in reasoning tasks, ranging from the correctness of software to the properties of formal systems, have been the focus of considerable research over the last two decades. This workshop brings together designers, implementors and practitioners to discuss various aspects impinging on the structure and utility of logical frameworks, including the treatment of variable binding, inductive and co-inductive reasoning techniques and the expressiveness and lucidity of the reasoning process.