Drawing Trees

We formally prove in Isabelle/HOL two properties of an algorithm for laying out trees visually. The first property states that removing layout annotations recovers the original tree. The second property states that nodes are placed at least a unit of distance apart. We have yet to formalize three additional properties: That parents are centered above their children, that drawings are symmetrical with respect to reflection and that identical subtrees are rendered identically

Code Generation for a Simple First-Order Prover

We present Standard ML code generation in Isabelle/HOL of a sound and complete prover for first-order logic, taking formalizations by Tom Ridge and others as the starting point. We also define a set of so-called unfolding rules and show how to use these as a simple prover, with the aim of using the approach for teaching logic and verification to computer science students at the bachelor level

Natural Deduction and the Isabelle Proof Assistant

We describe our Natural Deduction Assistant (NaDeA) and the interfaces between the Isabelle proof assistant and NaDeA. In particular, we explain how NaDeA, using a generated prover that has been verified in Isabelle, provides feedback to the student, and also how NaDeA, for each formula proved by the student, provides a generated theorem that can be verified in Isabelle.<br/

Teaching Intuitionistic and Classical Propositional Logic Using Isabelle

We describe a natural deduction formalization of intuitionistic and classical propositional logic in the Isabelle/Pure framework. In contrast to earlier work, where we explored the pedagogical benefits of using a deep embedding approach to logical modelling, here we employ a logical framework modelling. This gives rise to simple and natural teaching examples and we report on the role it played in teaching our Automated Reasoning course in 2020 and 2021.Comment: In Proceedings ThEdu'21, arXiv:2202.0214