Prolog

• Prolog is available on esus at /usr/bin/pl
• Prolog source files should have a suffix of .pl
• You can load a Prolog source file into the Prolog environment by typing consult('whatever.pl').
• You can break a list apart using [a|b] where a denotes the first item in the list and b denotes the rest of the list.
• To test for inequality, use \=
• You can trace one query by typing trace.
• You can exit the Prolog environment by typing halt.

Examples

Look at the file examples.pl.

Exercises

1. Construct a Prolog genealogy database that covers 3 generations of your family. You may use the following facts in your database: male(x), female(x), and parent(x, y) where x is the parent of y.
   • Define mother(X,Y).
   • Define father(X,Y).
   • Define grandmother(X,Y).
   • Define grandfather(X,Y).
   • Define allgrandparents(X,Y). This predicate should find and print all grandparents of Y.
   • Define sibling(X,Y). Make sure that a person is not his or her own sibling!
   • Define allsiblings(X,Y). This predicate should find and print all siblings of Y.
   • Define aunt(X,Y).
   • Define uncle(X,Y).
2. Define a function that counts the number of top level elements in a Prolog list.