Question

3. 2 marks] Write the rule remdup (List1, List2) that takes as input List1 and produces as output List2. List2 contains all items that appear in List1, except that repeated or duplicate items are not present in List1. For example: ?- remdup([1,2,3] ,x) ?- remdup([3,1,2,31,x) X=[1, 2, 3]. Note that the order of items in List2 is unspecified: for instance, [3,1,2 is an acceptable result for the second example above. 4. 2 marks Consider a course database that records the following facts offer(courseCode, semest. This states when a course is offered requires(courseCode, prerequisite). This states that prerequisite must be completed be- fore enrolling in courseCode. Write the predicate allreqs (Course, Reqs) that, given course code Course, determines a list of prerequisites Reqs

Solve above using prolog!!

Answer 1

Answer

3.

%rule remdup(List1,List2) that takes as input List1 and produces as output List2.
%List2 contains all items that appear in List1,
%except the repeated or duplicate items.

%if the List1 is empty, return the empty list. Base case.
remdup([],[]).

%if the first element of List1 is anywhere in the rest of List1, then call remdup
%with the rest of List1 as input.
remdup([H|T],C):- member(H,T),remdup(T,C).

%if the first element of List1 is not anywhere in the rest of List1, then append it to List2
%and call remdup with the rest of List1 as input.
remdup([H|T],[H|C]):- not(member(H,T)),remdup(T,C).

Sample Output

1 %rule rendup(List1,List2) that takes as input List1 and produces as output List2. 2 %List2 contains all items that appear in List!' 3 %except the repeated or duplicate items. 4 5 %if the List! is empty, return the empty list. Base case. 6remdup() 7 8 %if the first element of List1 is anywhere in the rest of List1, then call remdup 9 %with the rest of List1 as input. ie rendup(에T],c):-member(H, T).cenduR(T,C). 12 %if the first element of List1 is not anywhere in the rest of List1, then append it to List2 13 %and call remdup with the rest of List1 as input. 4 remdup([HIT],[Hc] not (member (H,T)),remduR(T,c) ?- remdup ([1,2,3],X) -remdup([3,1,2,3],x)

4.

%find all the direct prerequisites of the course.
prereqs(C,R):- requires(C,R).
%find all the indirect prerequisites of the course.
prereqs(C,R):- requires(C,R0),prereqs(R0,R).

%find all the prerequisites of the course.
allreqs(C,L):- setof(C1,prereqs(C,C1),L).

Sample Output

8 requires (102,101) 9 requires (106,102) 10 requires (106,103) 11 requires (105,184) 12 requires (104,101) 13 requires (105,103) 14 15%find all the direct prerequisites of the course 16 prereqs(C,R):- requires(C,R). 17%find all the indirect prerequisites of the course. 18 prereqs (C,R): - requires (C, Re), prereqs (Re, R) 19 20 find all the prerequisites of the course. 21 allreqs (C,L):- setof (C1,prereqs (C, C1), L) 23 24 2- allreqs (106, L) L-[101, 102, 103]