On Nov 20, 11:52 pm, Frederick Williams <freddywilli...@btinternet.com> wrote: > Graham Cooper wrote: > > > Exactly the same way we use not(). > > > Failure to return a result can be programmed for ANY PREDICATE > > > *WITH A FINITE DOMAIN* > > > [...] > > > You can PROGRAM the predicate NOT(...) > > > for any predicate with a FINITE SET OF ARGUMENT VALUES! > > Is this "negation as failure"? >
It's Negation as OTHER.
You can hand program Negation in prolog code for any predicate with a finite domain.
refundable(CUST) :- taxtype( CUST, personal ) refundable(CUST) :- taxtype( CUST, business ) refundable(CUST) :- taxtype( CUST, company ) not(refundable(CUST)) :- taxtype(CUST, other)
if( refundable(C) , processreturn(C) ).
This works for BOOLEAN ARG predicates like if, or, and, iff, xor, nand, nor, ..