The Sequent Calculus Calculator

This is the abstract that will be part of the magazine, the management summary and the poster. The abstract of thetechnical report will be similar but more technical.

The sequent calculus is the most widely used style of formal proof in computer science. Its applications includeproving logical statements correct and checking the type correctness of programs. The sequent calculus is taught aspart of the computer science bachelor curriculum at the HSR.

Learning the sequent calculus on paper involves copying a lot of large formulae and is therefore tedious. Mechanicalchecks cannot be performed when proving on paper, which makes the process error-prone. A few online web-basedinteractive proof assistants already exist. Unfortunately, none of them are currently suitable for use as a didactic aid at the HSR. Given the popularity of the sequent calculus, it would be advantageous to have a well engineered,interactive, web-based proof assistant as a learning aid for the sequent calculus.

This project has resulted in a web-based proof assistant written in a functional programming language that can be usedas a didactic aid to teach several different calculi in the sequent calculus style. The solution is extendable and newcalculi can be added to the application. Drag and drop style proofs can easily be performed by the web application. Thecore of the application is independent of the web frontend and can be used with other interfaces.

The thesis shows the possibilities and also the corresponding limits of sequent calculus style proofs that can beperformed in web applications.