CSE 428: Quizzes

Spring 2001, CSE 428: Quiz 11.1 - 19 April 2001

Please write your Name and Student ID at the top of the page. By default, this quiz will be returned in Section 2 (morning section).

[Pts 2] Difference lists in logic programming are (only one answer, please)
- The differencial of a list wrt one of the elements
- Lists in which all the elements are pairwise different
- A way of computing the difference of all the elements (which must be pairs)
- A way of representing lists so that the concatenation can be done in linear time
[Pts 2] Consider the standard way of representing trees in logic programming, and the following definition of a predicate p:
```
   p(empty,[]).
   p(node(T1,X,T2),[X|L]) :-
       p(T1,L1), p(T2,L2), append(L1,L2,L).
         /* append is the predefined list concatenation */
```
Consider now the query ?- p(t,L). where t is a term representing a certain tree. What is the result returned by it? (only one answer, please)
- L is the list of all the internal nodes of t
- L is the list of all the nodes in the frontier of t
- L is the list of all the nodes of t according to the preorder traversal
- L is the list of all the nodes of t according to the postorder traversal
[Pts 2] Consider the Prolog query ?- X = 1+2, Y is X+3. What is the result returned by it? (only one answer, please)
- error
- X = 3 Y = 6
- X = 1+2 Y = 6
- X = 1+2 Y = 1+2+3
[Pts 2] Consider the Prolog query ?- not(X=2). What is the result returned by it? (only one answer, please)
- no
- yes
- error
- X = 0; X = 1; X = 3; X = 4; ... (infinitely many answers)
[Pts 2] Assume given a Prolog program consisting only of the clause p :- p. and consider the query ?- p, r. What is the result returned by this query? (only one answer, please)
- no
- yes
- no answer, the query generates an infinite loop
- error, because r is not defined