Colimits are a useful tool for the combination of specifications and logical theories. We generalize the notion of colimit to a heterogeneous multi-logic setting. For practically realistic cases, the notion has to be weakened. We describe an algorithm that approximates the weaker notion but obtains a colimit whenever possible. This algorithm is being implemented as part of the Heterogeneous Tool Set HETS.

Software merging is a common and essential activity during the lifespan of large-scale software systems. Traditional textual merge techniques are inadequate for detecting syntactic merge conflicts. In this paper, we propose a domain-independent approach for syntactic software merging that exploits the graph-based structure(s) of programs. We use morphisms between fuzzy graphs to capture the relationships between the structural elements of the programs to be merged, and apply a truth ordering lattice to express inconsistencies and evolutionary properties as we compute the merge. We demonstrate the approach with a three-way consolidation merge in a commercial software system; in particular, we show how analyzing merged call structures can help developers gain a better understanding and control of software evolution. 1