an extension point for specializations of the weak negation tag name.
@style: defines a reference to a semantic profile. See
http://consumer.ruleml.org/1.02/glossary/#.40style
Negation As Failure formulas accept the header patter common to truth-valued connectives.
Negation As Failure formulas contain a single role.
an extension point for stripe skipping as well as specializations of the weak tag name in weak negations.
The negation role contains a single formula.
formulas allowed to belong to weak negation formulas include atomic forumulas.