logiikassa

Logiikassa is an open-source framework for formal logic and automated reasoning designed to support the development, verification, and teaching of logical systems. It provides a modular, extensible environment in which users can specify logics, build proofs, and integrate with external solvers. The project emphasizes clarity, interoperability, and reproducibility.

Inception and history: The project began as a collaboration among researchers in Finland, Sweden, and Norway under the Nordic Logic Initiative in 2017. The first public release appeared in 2019, followed by major updates in 2021 and 2023. It is maintained by an international community and a governing foundation.

Design and features: Logiikassa consists of a logic kernel that supports various deduction systems (sequent calculus, natural deduction, and tableau methods), a proof assistant interface, and a library of formalized logics including classical, intuitionistic, modal, and temporal logics. It includes a solver backend using SAT/SMT techniques, a graph-based proof visualization, and a plugin system for new logics, tactics, and exporters. The platform emphasizes interoperability, with import/export in standard formats (TPTP, JSON-LD) and bindings for Python and Rust.

Applications and reception: Widely used in university courses on logic, formal methods, and theoretical computer science, Logiikassa also supports research in formal verification and knowledge representation. It is regarded as a practical tool for prototyping new logics and for teaching rigorous proof construction.

Governance and licensing: Logiikassa is developed as an open-source project under a permissive license and stewarded by a non-profit foundation that coordinates contributions, documentation, and events.