Ribbon Tensorial Logic
Paul-André Melliès · 2018
We introduce a topologically-aware version of tensorial logic, called ribbon tensorial logic. To every proof of the logic, we associate a ribbon tangle which tracks the flow of tensorial negations inside the proof. The translation is functorial: it is performed by exhibiting a correspondence between the notion of dialogue category in proof theory and the notion of ribbon category in knot theory. Our main result is that the translation is also faithful: two proofs are equal modulo the equational theory of ribbon tensorial logic if and only if the associated ribbon tangles are equal up to topological deformation. This "proof-as-tangle" theorem may be understood as a coherence theorem for balanced dialogue categories, and as a mathematical foundation for topological game semantics.