%query: bin_tree(i). %% bin_tree(T) :- T is a tree. %% %TWTYPES :- type bin_tree(tree). bin_tree(void). bin_tree(tree(_, Left, Right)) :- bin_tree(Left), bin_tree(Right). /*TWDESC bin_tree(T) :- T is a tree. */ /*TWTYPES tree(void). tree(tree(V,L,R)) :- poly(V), tree(L), tree(R). poly(dummy). */ /*TWDEMO selected_norms([tree,poly]). query(bin_tree(b,f)). query(bin_tree(f,b)). */