Definition (DL Axiom). A description logic axiom is either
- a general concept inclusion of the form C ⊑ D for concepts C and D, or
- an individual assertion of one of the forms C(a), R(a, b), ¬R(a, b), a = b or a ≠ b for individuals a, b and a role R, or
- a role assertion of one of the forms R ⊑ S, R1 ◦ … ◦ Rn ⊑ S, Asy(R), Ref(R), Irr(R), Dis(R, S)
for roles R, Ri, S