Letter Tree Definition

ltree([ [b, [a, [r, [k, bark]]]],
        [c, [a, [r, [r, [y, carry]]],
                [t, cat,
                    [e, [g, [o, [r, [y, category]]]]]]]],
        [d, [e, [l, [a, [y, delay]]]]],
        [h, [e, [l, [p, help]]],
            [o, [p, hop,
                    [e, hope]]]],
        [q, [u, [a, [r, [r, [y, quarry]]]],
                [i, [z, quiz]],
                [o, [t, [e, quote]]]]]
      ]).

• An Ltree is a list of branches
• A branch is a list
• The first element of the list is a character.
• Each succeeding element is either another branch or the lexical entry for a word.
• The elements are in a specific order: the lexical entry comes fist, and branches are in alphabetical order by their first letters.