Nested Concept Graphs with Cuts: Mathematical Foundations

Conceptual graphs (CGs) have been developed as a graphic representation system for logic with the very goal to be humanly readable and understandable. They are designed to serve in different fields, one of them is information extraction. The best example for this is querying (relational) databases. There are different symbolic query languages, but these languages got a reputation of either being to restricted or to difficult to learn. Using CGs for querying relational databases, we can cope with this problem: As argued in [DH03]), nested CGs cover the whole expressiveness of SQL2, including negation and set functions, while being still comprehensible. In this pape