‫علمتني الثلوج أن أكون كبياض الثلج‬
‫ال يحمل قلبي غير الحب والعطف والرحمة ال‬
‫أسيئ الظن باألخرين وال أحكم عليهم من‬
‫مظهرهم فإذا لم تعاشرهم فأنت تجهلهم !‬
‫الذكاء االصطناعي‬
Artificial Intelligence ( AI)
comp323
Lab (2)
Knowledge Base 3
happy(vincent).
listensToMusic(butch).
playsAirGuitar(vincent):listensToMusic(vincent),
happy(vincent).
playsAirGuitar(butch):happy(butch).
playsAirGuitar(butch):listensToMusic(butch).
how many
clauses in the
KB3 ?
What does
this rule mean?
if we posed the query
?- playsAirGuitar(vincent).
?- playsAirGuitar(butch).
playsAirGuitar(butch):happy(butch).
playsAirGuitar(butch):listensToMusic(butch).
• We could replace the pair of rules given above by the
single rule
playsAirGuitar(butch):happy(butch);
listensToMusic(butch).
Knowledge Base 4
woman(mia).
woman(jody).
woman(yolanda).
loves(vincent,mia).
loves(marcellus,mia).
loves(pumpkin,honey_bunny).
loves(honey_bunny,pumpkin).
• for the first time we’re going to make use of
variables
?- woman(X).
• Let’s try a more complicated query, namely
?- loves(marcellus,X),woman(X).
Knowledge Base 5
loves(vincent,mia).
loves(marcellus,mia).
loves(pumpkin,honey_bunny).
loves(honey_bunny,pumpkin).
jealous(X,Y) :- loves(X,Z),loves(Y,Z).
Suppose we pose the query:
?- jealous(marcellus,W).
Prolog Syntax
• what are facts, rules, and queries built out of?
• The answer is terms, and there are four kinds of
terms in Prolog: atoms, numbers, variables, and
complex terms (or structures).
• Atoms and numbers are lumped together under
the heading constants,
• and constants and variables together make up
the simple terms of Prolog.
Atoms
1. A string of characters made up of upper-case
letters, lower-case letters, digits, and the
underscore character, that begins with a lowercase letter. For example:
butch, big_kahuna_burger, and m_monroe2.
Atoms
2. An arbitrary sequence of character enclosed
in single quotes. For example ’Vincent’, ’The
Gimp’, ’Five_Dollar_Shake’, ’&^%&#@$ &*’, and
’ ’. The character between the single quotes is
called the atom name.
Atoms
3. A string of special characters. For example:
@= and ====> and ; and :- are all atoms. As we
have seen, some of these atoms, such as ; and :have a pre-defined meaning
Numbers
• integers (that is: ... -2, -1, 0, 1, 2, 3, ...) are
useful for such tasks as counting the elements
of a list
Variables
• A variable is a string of upper-case letters,
lower-case letters, digits and underscore
characters that starts either with an uppercase letter or with underscore.
• For example, X, Y, Variable, _tag, X_526, and
List, List24, _head, Tail, _input and Output are
all Prolog variables.
Complex terms
• Complex terms are build out of a functor
followed by a sequence of arguments.
• The arguments are put in ordinary brackets,
separated by commas, and placed after the
functor.
• The functor must be an atom. That is,
variables cannot be used as functors.
• On the other hand, arguments can be any kind
of term.
• For example, playsAirGuitar(jody)
• its functor is playsAirGuitar
• and its argument is jody
• The number of arguments that a complex
term has is called its arity
arity
• Arity is important to Prolog. Prolog would be
quite happy for us to define two predicates
with the same functor but with a different
number of arguments
• it is usual to use a suffix / followed by a
number to indicate the predicate’s arity
• To return to KB2
• listensToMusic/1
• happy/1
• playsAirGuitar/1
Practical Session 1
?- listing.
command is to display the contents of the
current knowledge base
?- listing(playsAirGuitar).
References
• Prolog note
H.W ( group )
• Exercise 1.1
– 1,2,3,6,9
• Exercise 1.2
– 1,2,3
• Exercise 1.3
• Exercise 1.4
– 2,3
• Exercise 1.5
– 2,5,7