PAL Queries
PAL allows a user to add logical queries to a knowledge base, beyond the built-in querying facility of Protégé-2000. For example, in the newspaper sample project, you might want to find all the employees who form a team; that is, employees whose responsible editor is responsible for more than one employee (i.e., this query might translate to finding all the instances of the class Employee that are values for the slot responsible_for of an instance of the class Editor which has more than 1 value for its responsible_for slot).
The syntax for PAL queries is very similar to the one for PAL constraints. PAL supports writing arbitrary queries about the contents of a knowledge base. PAL queries are modeled with special-purpose frames and thus also can be saved as part of the knowledge base. PAL queries can be executed with the PAL querying engine.
Introduction/PAL Queries
Next: Enabling PAL Queries