QL Specification: Fix mistake in dispatch computation

Author: alexet

docs/language/ql-handbook/language.rst

@@ -341,7 +341,7 @@ A value ``v`` is in a type ``t`` under any of the following conditions:
 
 An ordered tuple *satisfies a predicate* ``p`` under the following circumstances. If ``p`` is not a member predicate, then the tuple satisfies the predicate whenever it directly satisfies the predicate.
 
-Otherwise, the tuple must be the tuple of a fact in the store with predicate ``q``, where ``q`` has the same root definition as ``p``. The first element of the tuple must be in the type before the dot in ``q``, and there must be no other predicate that overrides ``q`` such that this is true (see `Classes <#classes>`__ for details on overriding and root definitions).
+Otherwise, the tuple must be the tuple of a fact in the store with predicate ``q``, where ``q`` shares a root definition with ``p``. The first element of the tuple must be in the type before the dot in ``q``, and there must be no other predicate that overrides ``q`` such that this is true (see `Classes <#classes>`__ for details on overriding and root definitions).
 
 An ordered tuple ``(a0, an)`` satisfies the ``+`` closure of a predicate if there is a sequence of binary tuples ``(a0, a1)``, ``(a1, a2)``, ..., ``(an-1, an)`` that all satisfy the predicate. An ordered tuple ``(a, b)`` satisfies the ``*`` closure of a predicate if it either satisfies the ``+`` closure, or if ``a`` and ``b`` are the same, and if moreover they are in each argument type of the predicate.