描述逻辑概述

Description logics (DLs)

notations:

1、descriptions.   atomic concepts (unary predicates) & atomic roles (binary predicates)

2、equipped with a formal, logic-based semantics

 

two parts:

1、TBox (terminogical)：stating properties of concepts and roles, and relationships.                      corresponding to shema in database

2、ABox（assertional):   describing a concrete situation by stating properties of individuals.          corresponding to data in database

 

modern DL system:

deducing implicit knowledge to explicit knowledge automatically in infinit time by ABox and TBox.

subsumption algorithm, instance algorithm, consistency algorithm.

 

a basic DL —— ALC

ALC stands for "Attributive concept Language with Complements"

The DL that includes just this set of constructors (i.e., conjunction, disjunction, negation, existential restriction and value restriction) is called ALC.