Another Example

In predicate calculus :

now pick a few students :

	student(patrick) student(jane) 
	student(gwyn) student(ahmed)
	student(helen) student(vijay)

those with money left / free time :

	money-left(gwyn)	free-time(ahmed)	
	money-left(jane)	free-time(jane)
	money-left(helen)	free-time(vijay)

Translation Into Prolog :

holiday(X) :-
	student(X),
	money_left(X).

party(X) :-
	student(X),
	free_time(X). 

lucky(X) :-
	student(X), money_left(X) ;
	student(X), free_time(X).

student(patrick).
student(jane).
student(gwyn).
student(ahmed).
student(helen). 
student(vijay).
money_left(gwyn). 
free_time(ahmed).        
money_left(jane).        
free_time(jane).
money_left(helen).       
free_time(vijay).

Things to note :

• Layout : Keep it readable.
• Spaces, Hyphens and Underscores.
• Full stops and commas.
• The Universe of discourse (limited to that defined by the program)