FamTree01

A simple family tree is defined, some facts about the members are defined in the fact section, some rules connecting the family members are defined in the rule section.

This is an example of using Prolog to perform deduction.

Source Code

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/* Title : Family Tree Author : Michael Mui Version : 25/10/2013 Remarks : Perform query according to the following family tree betty(f) ricky(m) |------------| | |-------|---------|--------| ryan(m) mary(f) peter(m) kit(f) | | john(m) | | annie(f) |--------| |------| | | george(m) sandy(f) */ % Facts % ============================ % gender male(ricky). male(ryan). male(peter). male(john). male(george). female(betty). female(mary). female(kit). female(annie). female(sandy). % parent parent(betty,ryan). parent(ricky,ryan). parent(betty,mary). parent(ricky,mary). parent(betty,peter). parent(ricky,peter). parent(betty,kit). parent(ricky,kit). parent(mary,george). parent(john,george). parent(peter,sandy). parent(annie,sandy). % Rules % ============================ % mother mother(X,Y) :- parent(X,Y), female(X). % father father(X,Y) :- parent(X,Y), male(X). % sibling sibling(X,Y) :- parent(Z,X), parent(Z,Y), X \= Y. % brother brother(X,Y) :- sibling(X,Y), male(X). % sister sister(X,Y) :- sibling(X,Y), female(X). % grandparent grandparent(X,Z) :- parent(X,Y), parent(Y,Z). % ancestor ancestor(X,Y) :- parent(X,Y). ancestor(X,Y) :- parent(Z,Y), ancestor(X,Z). /* % Sample query % ============================ % who is the mother of kit ?- mother(X,kit). % who are the brothers of kit ?- sibling(X,kit). % who are the grandparents of kit ?- grandparent(X,sandy). % who are the ancestors of george ?- ancestor(X,george). */

Output

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Start the swi-prolog console, load the above script(fam01.pl) and query the system as follows: # prolog Welcome to SWI-Prolog (Multi-threaded, 32 bits, Version 5.10.4) Copyright (c) 1990-2011 University of Amsterdam, VU Amsterdam SWI-Prolog comes with ABSOLUTELY NO WARRANTY. This is free software, and you are welcome to redistribute it under certain conditions. Please visit http://www.swi-prolog.org for details. For help, use ?- help(Topic). or ?- apropos(Word). ?- ['fam01.pl']. % fam01.pl compiled 0.00 sec, 4,564 bytes true. ?- male(X). X = ricky ; X = ryan ; X = peter ; X = john ; X = george. ?- mother(X,george). X = mary ; false. ?- mother(X,Y). X = betty, Y = ryan ; X = betty, Y = mary ; X = betty, Y = peter ; X = betty, Y = kit ; X = mary, Y = george ; X = annie, Y = sandy. ?- sibling(X,george). false. ?- sibling(X,mary). X = ryan ; X = ryan ; X = peter ; X = peter ; X = kit ; X = kit ; false. ?- halt. #