Leo-III is an automated theorem prover for extensional type theory with Henkin semantics and choice. Reasoning with primitive equality is enabled by adapting paramodulation-based proof search to higher-order logic. The prover may cooperate with multiple external specialist reasoning systems such as first-order provers and SMT solvers. Leo-III is compatible with the TPTP/TSTP framework for input formats, reporting results and proofs, and standardized communication between reasoning systems, enabling, e.g., proof reconstruction from within proof assistants such as Isabelle/HOL. Leo-III supports reasoning in polymorphic first-order and higher-order logic, in many quantified normal modal logics, as well as in different deontic logics. Its development had initiated the ongoing extension of the TPTP infrastructure to reasoning within non-classical logics.

Leo-III是具有Henkin语义和选择的可扩展类型理论的自动定理证明器。通过使基于副调制的证明搜索适应高阶逻辑，可以实现基本相等的推理。证明者可以与多个外部专家推理系统（例如一阶证明者和SMT求解器）合作。Leo-III与TPTP / TSTP框架兼容，可用于输入格式，报告结果和证明以及推理系统之间的标准化通信，从而可以从例如Isabelle / HOL的证明助手中进行证明重建。Leo-III支持多态一阶和高阶逻辑，许多量化的正常模态逻辑以及不同的宗法逻辑中的推理。