Question

Logic Programming An important type of programming language is designed to reason using the rules of predicate logic. Prolog (from Programming in Logic), developed in the 1970s by computer scientists working in the area of artificial intelligence, is an example of such a language. Prolog programs include a set of declarations consisting of two types of statements, Prolog facts and Prolog rules. Prolog facts define predicates by specifying the elements that satisfy these predicates. Prolog rules are used to define new predicates using those already defined by Prolog facts. Example: Consider a Prolog program given facts telling it the instructor of each class and in which classes students are enrolled. The program uses these facts to answer queries concerning the professors who teach particular students. Such a program could use the predicates instructor(p.c) and enrolled(s.c) to represent that professor p is the instructor of course c and that students is enrolled in course c, respectively. For example, the Prolog facts in such a program might include: instructor(chan, math273) instructor(patel, ee222) instructor(grossman, cs301) enrolled (kevin, math273) enrolled (juana, ee222) enrolled (juana,cs301)

Answer 1

The answer is given below:

Fact:

instructor(chan,math273).
instructor(patel,ee222).
instructor(grossman,cs301).
enrolled(kevin,math273).
enrolled(juana,ee222).
enrolled(juana,cs301).
enrolled(kiko,math273).
enrolled(kiko,cs301).
teaches(P,S) :-instructor(P,C), enrolled(S,C).

The answer for queries is given below:

a)

instructor(chan,math273)

The output returned by above query is true because fact instructor(chan,math273) was provided as input.

It returns:

true

b)

instructor(patel,cs301)

The output returned by above query is false.

It returns:

false

c)

enrolled(X,cs301)

above query will return multiple answers juana and kiko because juana and kiko both enrolled in course cs301.

In query X is a variable, prolog will try to match expression enrolled(X,cs301) with facts from top to bottom and return answer.

it returns:

X = juana

X = kiko

d)

enrolled(kiko,Y)

above query will return multiple answers math273 and cs301 because kiko enrolled in course math273 and cs301.

In query Y is a variable, prolog will try to match expression enrolled(kiko,Y) with facts from top to bottom and return answer.

It returns:

Y = math273

Y = cs301

e)

teaches(grossman,Y)

above query will return multiple answers juana and kiko because professor grossman teaches to student juana and kiko.

In query Y is a variable, prolog will try to match expression teaches(grossman,Y) with facts from top to bottom and return answer.

It return:

Y = juana

Y = kiko