/*
 * Filename:  mc5.pro  (marriage counsellor 5)
 *
 * Programmer:  Br. David Carlson
 *
 * Date of creation:  September 4, 1993
 *
 * Revised:  December 11, 1999
 *
 * Description:
 *
 *     This program is used to predict the likelihood that 2 people have
 * (or will have) marriage problems.  Use the goal:  
 *    problems(marriage, Probability).
 * You can also submit other goals such as:
 *    problems(psychological, Probability),
 * Finally, you can try goals such as:
 *    success(marriage, Probability).
 */

problems(marriage, Prob) :- problems(financial, FinProb),
   problems(sexual, SexProb), 
   problems(communications, CommProb),
   problems(psychological, PsychProb), 
   problems(parental_divorce, ParDivProb),
   average5(FinProb, SexProb, CommProb, PsychProb, ParDivProb, Prob).
   
problems(financial, 1.0) :- unemployed(husband), unemployed(wife).
problems(financial, 0.8) :- underemployed(husband), unemployed(wife).
problems(financial, 0.8) :- unemployed(husband), underemployed(wife).
problems(financial, 0.5) :- underemployed(husband), underemployed(wife).

/* The 3 problems in the next section are seen as so important that the
 * resultant probability is the largest of the 3 probabilities, instead
 * of the average.
 */
problems(sexual, Prob) :- unfaithful(husband, HusbProb),
   unfaithful(wife, WifeProb),
   impotence(ImProb),
   maximum3(HusbProb, WifeProb, ImProb, Prob).
  
/* In the next section as well, the resultant probability is taken to be
 * the largest of the component probabilities.
 */
problems(communications, Prob) :- dominance(DomProb),
   abuse(AbuseProb), reticence(RetProb), 
   maximum3(DomProb, AbuseProb, RetProb, Prob).

problems(psychological, Prob) :- abuse(AbuseProb), 
   depression(DepressProb), psychosis(PsychProb),
   maximum3(AbuseProb, DepressProb, PsychProb, Prob).

problems(parental_divorce, 1.0) :- divorced_parents(husband),
   divorced_parents(wife), !.
problems(parental_divorce, 0.5) :- divorced_parents(husband), !.
problems(parental_divorce, 0.5) :- divorced_parents(wife), !.
problems(parental_divorce, 0.0).
      
dominance(Prob) :- domineering(wife, WifeProb),
   domineering(husband, HusbProb), maximum2(WifeProb, HusbProb, Prob).
   
abuse(Prob) :- abusive(husband, HusbProb), abusive(wife, WifeProb),
   maximum2(HusbProb, WifeProb, Prob).
      
reticence(Prob) :- reticent(husband, HusbProb), reticent(wife, WifeProb),
   average2(HusbProb, WifeProb, Prob).
   
depression(Prob) :- depressed(husband, HusbProb),
   depressed(wife, WifeProb), average2(HusbProb, WifeProb, Prob).
      
psychosis(Prob) :- psychotic(husband, HusbProb),
   psychotic(wife, WifeProb), average2(HusbProb, WifeProb, Prob).      
   
success(Area, Prob) :- problems(Area, ProblemProb), 
   Prob is 1 - ProblemProb.
   
average5(N1, N2, N3, N4, N5, Avg) :- Avg is (N1 + N2 + N3 + N4 + N5) / 5.

average3(N1, N2, N3, Avg) :- Avg is (N1 + N2 + N3) / 3.

average2(N1, N2, Avg) :- Avg is (N1 + N2) / 2.

maximum2(N1, N2, N1) :- N1 > N2, !.
maximum2(N1, N2, N2).

maximum3(N1, N2, N3, Max) :- N1 > N2, !, maximum2(N1, N3, Max).
maximum3(N1, N2, N3, Max) :- maximum2(N2, N3, Max).
   
/*  In the next section, fill in the data on the husband and wife to be
 *  counselled.
 */

unemployed(husband).
underemployed(wife).
unfaithful(husband, 0.3).
unfaithful(wife, 0.1).
impotence(0.1).
domineering(husband, 0.6).
domineering(wife, 0.0).
abusive(husband, 0.5).
abusive(wife, 0.0).
reticent(husband, 0.2).
reticent(wife, 0.6).
depressed(husband, 0.1).
depressed(wife, 0.4).
psychotic(husband, 0.0).
psychotic(wife, 0.0).
divorced_parents(wife).
divorced_parents(husband).