- ...[#BarGel94##1#,#Lif95##1#].
- Pereira and Alferes (1992) introduced a version of well-founded semantics that adheres to the so-called coherence principle which requires that strong negation implies weak negation. We will show later in Sect. 3 how the coherence principle can be introduced in our approach.
- ....
- Note
that for historical reasons we follow the convention that the minimal rules are
the preferred ones.
- ...form
- The seminormal form of 133#133
is
134#134

where 135#135 is the complement of

**c**. The term seminormal is taken from Reiter (1980). - ....
- Pereira and Alferes (1992) argue that each
extension of well-founded semantics to two types of negation should satisfy
what they call coherence principle: a weakly negated precondition should be
considered satisfied whenever the corresponding strongly negated literal is
derived. To model this principle in our approach one would have to weaken
the notion of
**X**-safeness even further. In the inductive definition, a rule**r**would have to be considered a member of 151#151 whenever for each weak precondition 152#152 of**r**- 153#153, or
- 154#154, where 155#155 if
**b**is an atom and**a**if 156#156.

- ...information:
- In realistic settings one would again use a
schema here. In order to keep the example simple we use the relevant instance
of the schema directly.

Thu Feb 8 10:26:15 MET 1996