Question

Incorrect Question 17 0/5 pts Complete the second rule of the following PROLOG program for last/2 where last(X,L) checks whether X is the last element of the list L. last(X,[X]). last(X,[LIT]):- (A) last([). (B) last(X,_). (C) last(X,T). (D) None of these (A) (B) (C) (D)

Answer 1

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Cola be Dicit.[:]) tool voor of solution: [P. (distup jump option : c le (last (X;T); odnose Justification : o tara su Paraphartoe les (x,x. 9. [Dicas de en to pomenicon last (X. [_11]):- ____ Mouse Cliot) for only to teil The I denotes a 'tail' or the Cinematome rest of the list! • With ? - last (c, x). prolog produces tists that have & as the last item. (According to your first definition) when you query 9- last (e [a, b, c))., st returns false because you haven't de fined a case for a list of only one item [x] or [x][]], so it fails , when list is shorter than two items.
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• However, last [[c], [a,b,c] Succeeds because you get [ b) _29] or whatever denoting that the tail part might be any list. So it !_29' can be '[c]', Satisfying the first définition like last (ſc), bicc]]). Remember that a nonempty list in prolog is actually a pair of the first list item Chead) and a list of the rest (tail). Usually written as TheadItoi]. Solution is last (x, [x]). last (x, [1T]):- last (X,T)