Constructing Recursive Data Structures: Trees

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A binary tree with a piece of information in each node:

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Use, for example, the functor tree/3

• Its first argument is the item of information
• The second and third ones are the left and right sons (subtrees)
• Use the constant void for empty trees

is_tree(void).
is_tree(tree(Info, Left, Right):- is_tree(Left),
is_tree(Right).

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Membership:

tree_member(Element, tree(Element, L, R)).
tree_member(Element, tree(E, L, R)):-
tree_member(Element, L).
tree_member(Element, tree(E, L, R)):-
tree_member(Element, R).