Programming 2012

Programming 2012
Laboratory session no. 2
Problem 1 (1p)
Ask Prolog the following queries:
• Does X unify with list [1,2,3,4];
• Does X unify with list whose head is 1;
• Does X unify with list whose first two elements are 1 and 2;
• Does X unify with a singleton list? Singleton list is a list of length 1;
• Does X unify with a list of length 3?
Problem 2 (1p)
Define in Prolog the predicates listed below:
• first(X) satisfied when X unifies with list [1,2,3,4];
• second(X) satisfied when X unifies with list whose head is 1;
• third(X) satisfied when X unifies with list whose first two elements are
1 and 2;
• fourth(X) satisfied when X unifies with a singleton list. Singleton list
is a list of length 1;
• fifth(X) satisfied when X unifies with a list of length 3?
Problem 3 (1p)
Define in Prolog predicate even/2 such that even(N) is satisfied when N is
an even number. Provide two implementations of the predicate. First using
modulo division and second – recursion.
Problem 4 (3p)
We represent binary trees with labelled internal nodes in Prolog using the
functor node/3 for internal nodes and the atom leaf/0 for leaves. E.g., the
structure:
represents the tree:
node(leaf, 3, node(leaf, 5, leaf))
3
5
1

Define predicates mirror/2, which creates the mirror image of a tree and
flatten/2, which creates a list of the tree labels in the infix order.
2