https://perso.ens-lyon.fr/olivier.laurent/yalla/

The initial specification was to get a library which:

• would provide standard results on the proof theory of Linear Logic;
• could be reused, thus in particular able to deal with some variants of the system;
• should be compatible with the Curry-Howard interpretation of proofs, thus faithful to their computational content.

We will describe the evolution of the project and how it matches this specification through the different versions of the library: Yalla 1, Yalla 2 (current version), Yalla 3 (future directions).

Following all previous known works, Yalla 1 defined proofs in Prop. It relies on an explicit exchange rule for dealing with the computational content of proofs. Yalla 2 corresponds to a move to Type to be able to extract computational informations from proofs. Yalla 3 will rely on a different way of approaching exchange to be able to deal with local transformations of proofs more easily.