/* ================================================================== */
/* Examples where you want to assume some deductively provable goals. */
/* ================================================================== */

/* =====================================================================
                Example 1: Paramedic Evaluation  
   
   Suppose you're a paramedic rushing to the O'Rorke residence.  Paul's
   ill and spread-eagled on the floor.  You check for signs of heart
   failure (perhaps he's just reviewed Aha's latest modifications to the
   AMAL research program).  One of the symptoms of heart failure might
   be a poor EKG reading.  Do you check your equipment at this time?
   Perhaps, if you're not fond of Paul, you'd check your ekg machine's
   batteries, monitor, and other components.  The more intelligent choice,
   however, is to save UCI's leading researcher before he knocks off.
   Thus you ASSUME that your ekg machine is in good shape.

   Note: It doesn't matter whether the machine can be prove deductively
   to be in good shape.
   ====================================================================== */

/*==== Domain Theory 1. ====*/
assumable(ekg_machine_works_properly(_),
          ekg_machine_works_properly(_)).

having_heart_attack(Person) :-
   bad_ekg_reading(Person),
   not_breathing(Person).

bad_ekg_reading(Person) :-
   my_ekg_machine(MyEkgMachine),
   ekg_machine_works_properly(MyEkgMachine),
   bad_reading(Person,MyEkgMachine).
ekg_machine_works_properly(Machine) :-
   good_batteries(Machine),
   good_monitor(Machine).

not_breathing(Person) :-
   no_pulse(Person),
   diagphram_not_moving(Person).

/*==== Example 1. ====*/
my_ekg_machine(machine1).
bad_reading(paul,machine1).
no_pulse(paul).
diagphram_not_moving(Person).
good_batteries(machine1),
good_monitor(machine1).

/*==== Query 1. ====*/
query1 :- 
  explain_and_learn((having_heart_attack(paul)),
                    (having_heart_attack(Anyone))).


/* ====================================================================== 
                Example 2: Flu detector

   This is NOT an especially good example to prove my point that some
   deductively provable goals should be assumable.  In this case, we assume
   that if a person's head feels warm and they are dizzy, don't bother to 
   check whether they have a high temperature before assuming that they have
   the flu.
   ====================================================================== */

/*==== Domain Theory 2. ====*/
assumable(high_temperature(_),high_temperature(_)).
   
has_flu(Person) :- 
   runny_nose(Person),
   fever(Person).
fever(Person) :-
   head_feels_warm(Person),
   dizzy(Person),
   high_temperature(Person).
high_temperature(Person) :-
   temperature(Person,Temperature),
   Temperature > 98.6.

/*==== Example 2. ====*/
runny_nose(david).
head_feels_warm(david).
dizzy(david).
temperature(david,500.0).

/*==== Starting Query 2. ====*/
query2 :-
  explain_and_learn((has_flu(david)),
                    (has_flu(GreatPerson))).


/* ======================================================================
               Example 3: Frustration Examplified

   Suppose you're answering an innocent little question that you're little
   runt-of-a-kid comes up with.  He's not satisfied and asks another.  Then
   another.  And another.  Until you're steamed up so much that you tell him
   there are some things you just don't know.  At least he can assume some
   things.  The point: you may be able to explain things forever...given
   infinite time, but you're tired and want to put the little kid to bed.
   ====================================================================== */

/*==== Domain Theory 3. ====*/
assumable(lots_of_lakes_west_of_here,lots_of_lakes_west_of_here).
assumable(wind_due_to_earth_rotation,wind_due_to_earth_rotation).
assumable(daddy_said_so,daddy_said_so).

/*==== (Read: "It rains because...the skies are cloudy."
        Then the kid asks: "Where do clouds come from?" 
        You answer: "Clouds come from lakes west of here and the winds
                     come from the west."
        He responds: "Why do the winds come from the west?" (assuming that,
                      yes indeed, there are lakes west of here)
        And it continues.
  ====*/ 
why_it_rains :- cloudy_sky.
cloudy_sky :- 
   lots_of_lakes_west_of_here,
   winds_come_from_west.
winds_come_from_west :-
   earth_rotates,
   wind_due_to_earth_rotation.
earth_rotates :- 
   earth_has_gravitational_attraction_to_sun.
earth_has_gravitational_attraction_to_sun :-
   einstein_said_so.
einstein_said_so :-
   einstein_studied_gravitation.
einstein_studied_gravitation :-
   daddy_said_so.

/*==== Thus, for example, you give up at some point, saying that Einstein 
       studied gravitation because "Daddy said so". Of course, the kid
       has an unusual explanation for his original question, but he knows
       when to stop (because you yelled at him last time after this point)
  ====*/

/*==== Starting Query 3. (The kid's original question.) ====*/
query3 :- why_does_it_rain.
why_does_it_rain :- explain_and_learn(why_it_rains,why_it_rains).