
Re: PROLOG does SO have NOT() !!
Posted:
Nov 20, 2012 3:33 PM


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, ..
nand(X) : not(X).
even if you nest them.
? or( if(1,0) , if(1,X) ) X = 1
Herc

