Equivalence of multiset-based consequence relations

Abstract

The pioneering work of Blok and J\'onsson and its further development by Galatos and Tsinakis initiated an abstract study of consequence relations using the tools of module theory, where consequence relations over all types of syntactic objects are put on an equal footing. However, the assumption that in a consequence relation the premises form merely a set, as opposed to a more complicated structure, is still retained. An attempt to extend this framework to account for inferentially substructural generalizations of consequence relations, where the premises have the structure of a finite multiset, was recently made by Cintula, Gil-F\'erez, Moraschini, and Paoli. In this paper, we develop a different inferentially substructural generalization of the work of Galatos and Tsinakis, where we instead assume that the premises have the structure of a set of finite multisets. This leads a somewhat smoother framework which, unlike that of Cintula et al., covers the original theory of Galatos and Tsinakis as a special case.