The Semantics of Entailment 0
Robert K. Meyer, EDWIN D. MARES · 1993
Abstract The system NR of relevant implication with modality was proposed in Meyer (1968) to combine the system R of relevant implication with the modal logic S4. This motivated a definition of entailment, in something like the sense of Anderson and Belnap (1975), as strict relevant implication. While NR exactly captures the entailment of certain fragments of the system E of entailment _ in particular, the pure calculus E → of entailment _ it was shown in Maksimova (1973) that there is a non-theorem of E which is provable on NR translation.