Handsome Non-Commutative Proof-Nets: perfect matchings, series-parallel orders and Hamiltonian circuits

This paper provides a definition of proof-nets for non-commutative linear logic (cyclic linear logic and Lambek calculus) where there are no links, that are small graphs representing the connectives. Instead of a tree like representation with links, the formula is depicted as a graph representing the conclusion up to the algebraic properties of the connectives. In the commutative case the formula is viewed as a cograph. In the non-commutative case it is a more complicated kind of graph which is, roughly speaking, a directed cograph. The criterion consists in the commutative condition plus a bracketing condition

Graph Algorithms for Improving Type-Logical Proof Search

Proof nets are a graph theoretical representation of proofs in various fragments of type-logical grammar. In spite of this basis in graph theory, there has been relatively little attention to the use of graph theoretic algorithms for type-logical proof search. In this paper we will look at several ways in which standard graph theoretic algorithms can be used to restrict the search space. In particular, we will provide an O(n^4) algorithm for selecting an optimal axiom link at any stage in the proof search as well as a O(kn³) algorithm for selecting the k best proof candidates