A Decidable Constraint Diagram Reasoning System

Constraint diagrams are a visual notation designed for use by software engineers to formally specify information systems. In this paper we formalize a fragment of the constraint diagram language. A set of reasoning rules are defined and we prove that this set is both sound and complete. Given constraint diagrams D₁ and D₂ such that D₂ is a semantic consequence of D₁, to prove completeness we construct a proof of D₂ from D₁. A decision procedure can be extracted from this proof construction process and it follows that the system is decidable.