This document contains a lecture on programming with Prolog III. It includes examples of facts and rules defining instructor and student relationships. It then shows example queries and their results. It poses sample test questions for students to check their understanding of writing predicates and rules in Prolog.

1. CSE240 – Introduction to
Programming Languages
Lecture 24:
Programming with Prolog III
Javier Gonzalez-Sanchez
javiergs@asu.edu
javiergs.engineering.asu.edu
Office Hours: By appointment

2. Javier Gonzalez-Sanchez | CSE 240 | Fall 2017 | 2
A program is Facts, Rules …
% facts
instructor(john,cs365).
instructor(mary,cs311).
instructor(paul,cs446).
enrolled(joseph,cs311).
enrolled(joseph,cs365).
enrolled(joseph,cs446).
enrolled(danielle,cs365).
enrolled(danielle,cs446).
% rules
teaches(P,S) :- instructor(P,C), enrolled(S,C).
classmates(S1, S2) :- enrolled(S1, C), enrolled(S2, C).

3. Javier Gonzalez-Sanchez | CSE 240 | Fall 2017 | 3
… and Queries (part 1 / 2)
?- enrolled (joseph, cs365).
true
?- enrolled (X, cs365).
X=joseph
X=danielle
?- teaches (X, joseph).
X=john
X=mary
X=paul
?- classmates (joseph, danielle).
true
?- classmates (joseph, jessica).
false
?- classmates (jessica, danielle).
false

4. Javier Gonzalez-Sanchez | CSE 240 | Fall 2017 | 4
… and Queries (part 2 / 2)
% An additional rule
classmates (S1, S2, C) :- enrolled (S1, C), enrolled (S2, C)
?- classmates (joseph, danielle, C).
cs365
cs446
?- classmates (joseph, jessica, C).
false
?- classmates (jessica, danielle, C).
false

5. Test Yourselves

6. Javier Gonzalez-Sanchez | CSE 240 | Fall 2017 | 6
Q1
What is the predicate logic expression equivalent to
"Charlie owns a computer"
owns(charlie, computer).

7. Javier Gonzalez-Sanchez | CSE 240 | Fall 2017 | 7
Q2
instructor(john,cs365).
instructor(mary,cs311).
enrolled(danielle,cs365).
enrolled(danielle,cs446).
• Which query provides a list of all the students enrolled in cs365?
enrolled(Who, cs365).

8. Javier Gonzalez-Sanchez | CSE 240 | Fall 2017 | 8
Q3
If weather is cold, everyone likes it.
Write this statement as a Prolog clause.
likes(X, weather) :- cold(weather).
%notice “weather” in lowercase

9. Javier Gonzalez-Sanchez | CSE 240 | Fall 2017 | 9
Q5
• Given the following facts
• cat(tom).
• black_spots(tom).
• dog(pluto).
• white_spots(pluto)
•
Which rule defines in Prolog the following sentence:
• "mary owns a Pet if it is a cat and it has black spots"
owns(mary, Pet):- cat(Pet), black_spots(Pet).

10. Javier Gonzalez-Sanchez | CSE 240 | Fall 2017 | 10
Q6
Which rule defines in Prolog the following sentence:
"If someone owns something, he loves it"
loves(Who, What):-owns(Who, What).

11. Javier Gonzalez-Sanchez | CSE 240 | Fall 2017 | 11
Q7
1
2
3
4

12. CSE240 – Introduction to Programming Languages
Javier Gonzalez-Sanchez
javiergs@asu.edu
Fall 2017
Disclaimer. These slides can only be used as study material for the class CSE240 at ASU. They cannot be distributed or used for another purpose.