.. include:: global.rst

.. _Overview:

Prolog Tutorial
###################################



Notes
====================================

The 3 basic ideas in prolog:

* Facts: Assertions about the world (e.g., "Socrates is a man").
* Rules: Conditional statements (e.g., "If someone is a man, they are mortal").
* Queries: Questions you ask the system (e.g., "Is Socrates mortal?").


Facts
-----------------

.. code-block::
    
    parent(bob, alice).
    parent(bob, bill).
    parent(alice, charlie).


Rules
-----------------

.. code-block::

    grandparent(X, Z) :- 
        parent(X, Y), 
        parent(Y, Z).

Queries
-----------------
?- parent(bob, alice).

Output: true.

Ask a Variable question:

?- parent(bob, Who).

Output: Who = alice ; (Press ; to see the next result)

Output: Who = bill.


    

.. csv-table:: Syntax Rules
    :header: "Feature", "Syntax Example", "Notes"

    Atoms,"apple, socrates",Must be lowercase.
    Variables,"X, Person",Must be uppercase.
    "The ""If""",:-,Separates the head from the body.
    "The ""And""",",",Used to link conditions in a rule.
    "The ""Or""",;,Used to provide alternatives.
    The End,.,Every statement must end with a period.



Code
====================================

.. literalinclude:: ./other/prolog/test.pl