isLeaf leaf true isLeaf cons u v false left cons u v u right cons u v v concat leaf y y concat cons u v y cons u concat v y less_leaves u v if1 isLeaf u isLeaf v u v if1 b true u v false if1 b false u v if2 b u v if2 true u v true if2 false u v less_leaves concat left u right u concat left v right v isLeaf 1 leaf 0 true 0 cons 2 false 0 left 1 right 1 concat 2 less_leaves 2 if1 4 if2 3 FULL ./TRS/SchneiderKamp/trs/thiemann05.trs