## Section: New Results

### A neutral approach to proof and refutation in MALL

Participants : Olivier Delande, Dale Miller, Alexis Saurin.

Given the team's previous efforts at building automated deduction systems that viewed finite success and finite failure as duals within a proof theory setting, we were intrigued to see if that duality could be extended beyond the simple, Horn clause setting. This past year, Olivier Delande and Miller described in the paper [16] a way to extend that notion of proving and refuting to the richer setting of MALL. They showed how it is possible in that logic to view moves in a game as contributing simultaneously to both a proof and a refutation of a given formula. Of course, only one of the players of such a game can be a winner. Delande, Miller, and Saurin have completed a comprehensive approach to this style of game in [27] .