% From John Kalman:
% 
%      (1) The input file %i1 below. This is Example 4.27 on page 83
% of my latest notes. It illustrates that looping is possible when
% for_sub is clear, and would be possible if backward subsumption were done
% before forward subsumption.

set(hyper_res).
clear(for_sub).                 % switch off forward subsumption
set(print_lists_at_end).
assign(max_given,15).           % stop after 15 given clauses
assign(stats_level,1).  % changed from 0 to 1 by McCune

list(usable).
  -P(x) | P(x).
end_of_list.

list(sos).
  P(a).
end_of_list.
  
