Part II: OWL - Foundations of Semantic Web Technologies

Blocking (in ALC)
y is blocked (by x) if
y is not an individual (but a variable),
y is a successor of x and L(y) ⊆ L(x),
or an ancestor of y is blocked.
R R R
a x y
>
∃R.>
>
∃R.>
>
∃R.>
y blocked by x in this example.
Blocking conditions for more expressive DLs are more involved;
the idea is the same.
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