CSE 428: Quizzes

Spring 2001, CSE 428: Quiz 11.3 - 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 1 (afternoon section).

[Pts 2] Consider the following definition of concatenation using difference lists:
```
   conc(X-Y,Y-Z,X-Z).
```
Consider now the query?- conc([1,2,3|L]-L,[4,5|K]-K,M).What is the result returned in M by this query? (only one answer, please)
- error
- The list [1,2,3,4,5]
- A list of the form [1,2,3,4,5|_G324], where _G324 is the representation of an internal variable (the number here does not matter, it may be different from 342)
- A list of the form [1,2,3,4,5|_G324]-_G324, where_G324is the representation of an internal variable
[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),L) :- 
     p(T1,L1), p(T2,L2), append(L1,L2,K), append(K,[X],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+Y, Y is 2+3. What is the result returned by it? (only one answer, please)
- error
- X = 6 Y = 5
- X = 1+5 Y = 5
- X = 1+2+3 Y = 2+3
[Pts 2] Consider the Prolog query ?- not(1=2). What is the result returned by it? (only one answer, please)
- no
- yes
- error
- no answer, the query generates an infinite loop
[Pts 2] To unify two terms t and u means (only one answer, please)
- to find a substitution sigma such that t = u sigma
- to find a substitution sigma such that t sigma = u
- to find a substitution sigma such that t sigma = u sigma
- to prove that the evaluations of t and of u produce the same result