.TH Files 5 "September 7, 1994"
.SH NAME
.B FileName.pl \- input file for
.I
Progol
.SH DESCRIPTION
All input for
.I
Progol
is read from a single file which has a ".pl" suffix.
The contents of this file are usually:
.RS
.TP
.B 1. Progol commands
including mode declarations and parameter settings.
.TP
.B 2. Background knowledge
as a set of Prolog clauses.
.TP
.B 3. Positive examples
as a set of definite clauses (not necessarily ground unit clauses).
.TP
.B 4. Negative examples
as a set of ground negative literals. 
.RE
Comments can appear anywhere in the file provided they are
prefaced by a "%" sign.
.SH EXAMPLES
Here is an example input file for learning list membership.
.sp 2
.DS 0 0
:- set(c,2)?
.br
%%%%%%%%%%%%%%%%%%%%%%%%%%%
.br
% Learns recursive clauses for member(Element,List)
.br
.br
:- modeh(1,member(-constant,+clist))?
.br
:- modeb(1,+constant = #constant)?
.br
:- modeb(1,+clist = [-constant|-clist])?
.br
:- modeb(1,member(-constant,+clist))?
.br

.br
%%%%%%%%%%%%%%%%%%%%%%%%%%%
.br
% Types
.br

.br
clist([]).
.br
clist([H|T]) :- constant(H), clist(T).
.br

%%%%%%%%%%%%%%%%%%%%%%%%%%%
.br
% Positive examples
.br

member(0,[0]).
.br
member(0,[0,0]).
.br
member(0,[1,0]).
.br
member(0,[2,0]).
.br
member(1,[0,1]).
.br
member(1,[1,1]).
.br
member(1,[1]).
.br
member(1,[2,1]).
.br
member(2,[2,2]).
.br
member(2,[2]).
.br
member(2,[3,2]).
.br
member(3,[2,3]).
.br
member(3,[3]).
.br
member(4,[3,4,5]).
.br
member(3,[4,2,3]).
.br
member(4,[4]).
.br

.br
% member(X,[X|_]).
.br
% member(X,[_,X|_]).
.br

.br
%%%%%%%%%%%%%%%%%%%%%%%%%%%
.br
% Negative examples
.br

.br
:- member(0,[1,2]).
.br
:- member(0,[1]).
.br
:- member(1,[0]).
.br
:- member(2,[3]).
.br
:- member(2,[]).
.br
:- member(3,[]).
.br
.DE
.SH "SEE ALSO"
set/2, mode/2