/*
   Paul Y Gloess, http://www.enseirb.fr/~gloess/
     Created on   26 April 2009,
     Last edition 26 April 2009.

   Purpose:
   -------

     sumto CLP(Qlin) example:

     sumto(N, S) means that 0+...+N = S.

*/

sumto(N, S) :-           % (sumtoZ).
  0 ^= N, 0 ^= S.
sumto(N, S) :-           % (sumtoP).
  1 ^<= N, N ^<= S, N-1 ^= NP, S-N ^= SN,
  sumto(NP, SN).	


/*
   reconsult(sumto),
     N+1 ^= S, sumto(N, S).

   reconsult(sumto),
     N+2 ^= S, sumto(N, S).

   reconsult(sumto),
     N+3 ^= S, sumto(N, S).

   reconsult(sumto),
     2*N ^= S, sumto(N, S).

*/