2019/02/11 by Philippe Balbiani, Balbiani, Philippe, Çiğdem Gencer +1
Business, Management and Accounting · Computer Science · #Advanced Computational Techniques and Applications #FOS: Computer and information sciences #Logic in Computer Science (cs.LO) #Optics and Image Analysis #Semantic Web and Ontologies
paper · pdf · doi:10.48550/arxiv.1902.03770
openalex publication_date 2019/02/11 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The unification problem in a normal modal logic is to determine, given a formula F, whether there exists a substitution s such that s(F) is in that logic. In that case, s is a unifier of F. We shall say that a set of unifiers of a unifiable formula F is complete if for all unifiers s of F, there exists a unifier t of F in that set such that t is more general than s. When a unifiable formula has no minimal complete set of unifiers, the formula is nullary. In this paper, we prove that KB, KDB and KTB possess nullary formulas.