/* 

  Inductive Logic Programming in Picat v3.

  This is a port of the program hyper.pl in
  I. Bratko, "Prolog Programming for Artificial Intelligence", 4th edn.,
  Pearson Education / Addison-Wesley 2012
  Page 507ff (Figure 21.7 and 21.3)
       
  The module hyper_v3 is here
  http://hakank.org/picat/hyper_v3.pi

  Final result (39ms):
  """
  Hypotheses generated: 85
  Hypotheses refined:   16
  To be refined:        29

  even([]).
  even([A,B|C]):-
    even(C).

  odd([A|B]):-
    even(B).
  """


  This Picat model was created by Hakan Kjellerstrand, hakank@gmail.com
  See also my Picat page: http://www.hakank.org/picat/

*/

import hyper_v3.

main => go.


go ?=>
  induce(H),
  show_hyp(H),
  nl.

go => true.


% Moved from from hyper_v3.pi
max_proof_length( 6).   % Max. proof length, counting calls to preds. in hypothesis
max_clauses( 4).        % Max. number of clauses in hypothesis
max_clause_length( 5).  % Max. number of literals in a clause


% Figure 21.8  Learning about odd-length and even-length simultaneously.

% Inducing odd and even length for lists

backliteral( even( L), [ type(L,list)], []).
backliteral( odd( L), [ type(L,list)], []).

term( list, [X|L], [ type(X,item), type(L,list)]).
term( list, [], []).

prolog_predicate( fail).

start_clause([ odd( L) ] / [ type(L,list)]).
start_clause([ even( L) ] / [ type(L,list)]).

ex( even( [])).
ex( even( [a,b])).
ex( odd( [a])).
ex( odd( [b,c,d])).
ex( odd( [a,b,c,d,e])).
ex( even( [a,b,c,d])).

nex( even( [a])).
nex( even( [a,b,c])).
nex( odd( [])).
nex( odd( [a,b])).
nex( odd( [a,b,c,d])).