Completeness Proof Strategies for Euler Diagram Logics

Abstract. Visual logics based on Euler diagrams have recently been developed, including generalized constraint diagrams and concept diagrams. Establishing the metatheories of these logics includes providing completeness proofs where possible. Completeness has been established for such logics, including Euler diagrams, spider diagrams and a fragment of the constraint diagram logic. In this paper, we identify commonality in their completeness proof strategies, showing how, as expressiveness increases, the strategy readily extends. We identify a fragment of concept diagrams and demonstrate that the completeness proof strategy does not extend to this fragment. Thus, we have established that the existing completeness proof strategies are limited. Consequently, we examine the challenge of devising new approaches to proving completeness in more expressive logics.