2020/10/14 by Silvio Ghilardi, Ghilardi, Silvio, Alessandro Gianola +3 · 1 citation
Computer Science · #FOS: Computer and information sciences #Formal Methods in Verification #Logic in Computer Science (cs.LO) #Logic, programming, and type systems #Natural Language Processing Techniques #cs.LO #semigroups and automata theory
paper · pdf · doi:10.48550/arxiv.2010.07082
openalex publication_date 2020/10/14 · arxiv created 2021/01/19 · arxiv updated 2021/01/21 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
In this paper, the theory of McCarthy's extensional arrays enriched with a maxdiff operation (this operation returns the biggest index where two given arrays differ) is proposed. It is known from the literature that a diff operation is required for the theory of arrays in order to enjoy the Craig interpolation property at the quantifier-free level. However, the diff operation introduced in the literature is merely instrumental to this purpose and has only a purely formal meaning (it is obtained from the Skolemization of the extensionality axiom). Our maxdiff operation significantly increases the level of expressivity; however, obtaining interpolation results for the resulting theory becomes a surprisingly hard task. We obtain such results via a thorough semantic analysis of the models of the theory and of their amalgamation properties. The results are modular with respect to the index theory and it is shown how to convert them into concrete interpolation algorithms via a hierarchical approach.