The calculus of facts

TLDR: This paper introduces a net theoretic version of the first-order predicate calculus, and shows how ‘static’ logic can be correctly applied even in those practically important dynamic contexts where certain sentences change their truthvalues in a not fully specified order.

Abstract: Nets of conditions and events (‘special’ Petri nets) are widely used models of dynamic systems. They represent the causal structure of the concurrent operation and co-operation of the components of a system. In this paper we introduce a net theoretic version of the first-order predicate calculus. Its purpose is to offer a formal language for expressing the relationship between a net model and the modelled system, and to provide rules for deriving the logical consequences of such an interpretation in a way that the results are expressed in the same language as the model, namely the net language. By this we permit the use of symbolic logic as part of a general formalism for the analysis and specification of dynamic systems. We show how ‘static’ logic can be correctly applied even in those practically important dynamic contexts where certain sentences change their truthvalues in a not fully specified order. As a useful by-product the graphical representation of nets induces a very natural graphical representation of the predicate calculus.