Modularity is a key requirement for large ontologies in order to achieve re-use, maintainability, and evolution. Mechanisms for ‘normalisation’ to achieve analogous aims are s...
Horn⊃ is a logic programming language which extends usual Horn clauses by adding intuitionistic implication in goals and clause bodies. This extension can be seen as a form of s...
An operation of concatenation is introduced for graphs. Then strings are viewed as expressions denoting graphs, and string languages are interpreted as graph languages. For a clas...
Phrase structure trees have a hierarchical structure. In many subjects, most notably in taxonomy such tree structures have been studied using ultrametrics. Here syntactical hierar...
—What is reachability in higher-order functional programs? We formulate reachability as a decision problem in the setting of the prototypical functional language PCF, and show th...