Description Logics (note the plural!)

• ALH is a special form of Description Logic

• A family of logics:

• • have separate categorization for classes, individuals, and roles
  • description logics differ from one another on what relationships are allowed among those
  • • the names of description logics types, like AL, ALH, ALCR+, SHIQ, etc, usually refer to what is allowed
    • • e.g., the letter H means that subclassing is allowed, I means that inverse roles can be defined, etc.
  • semantics is defined using model theory

• Description logics have been developed for knowledge representations, ontologies, formal thesauri, etc.