diff --git a/library/lists.yap b/library/lists.yap
index 96dff22e3..4e539019a 100644
--- a/library/lists.yap
+++ b/library/lists.yap
@@ -265,14 +265,14 @@ sublist(Sublist, [_|List]) :-
 %   is true when XList and YList only differ in that the elements X in XList
 %   are replaced by elements Y in the YList.
 substitute(X, XList, Y, YList) :-
-	'$substitute'(XList, X, Y, YList).
+	substitute2(XList, X, Y, YList).
 
-'$substitute'([], _, _, []).
-'$substitute'([X0|XList], X, Y, [Y|YList]) :-
+substitute2([], _, _, []).
+substitute2([X0|XList], X, Y, [Y|YList]) :-
 	X == X0, !,
-	'$substitute'(XList, X, Y, YList).
-'$substitute'([X0|XList], X, Y, [X0|YList]) :-
-	'$substitute'(XList, X, Y, YList).
+	substitute2(XList, X, Y, YList).
+substitute2([X0|XList], X, Y, [X0|YList]) :-
+	substitute2(XList, X, Y, YList).
 
 %   suffix(Suffix, List)
 %   holds when append(_,Suffix,List) holds. 
diff --git a/library/rbtrees.yap b/library/rbtrees.yap
index 9141bf7f3..93fab6565 100644
--- a/library/rbtrees.yap
+++ b/library/rbtrees.yap
@@ -378,15 +378,16 @@ fix_root(red(L,K,V,R),black(L,K,V,R)).
 insert2(black([],[],[],[]), K, V, Nil, T, Status) :- !,
 	T = red(Nil,K,V,Nil),
 	Status = not_done.
-insert2(red(L,K0,V0,R), K, V, Nil, red(NL,K0,V0,NR), Flag) :-
+insert2(red(L,K0,V0,R), K, V, Nil, NT, Flag) :-
 	( K @< K0
 	-> NR = R,
-	 insert2(L, K, V, Nil, NL, Flag)
+	  NT = red(NL,K0,V0,R),
+	  insert2(L, K, V, Nil, NL, Flag)
 	; K == K0 ->
 	  NT = red(L,K0,V,R),
 	  Flag = done
 	;
-	  NL = L,
+	  NT = red(L,K0,V0,NR),
 	  insert2(R, K, V, Nil, NR, Flag)
 	).
 insert2(black(L,K0,V0,R), K, V, Nil, NT, Flag) :-
@@ -471,7 +472,7 @@ fix_right(T,T,done).
 % simplified processor
 %
 %
-pretty_print(T) :-
+pretty_print(t(_,T)) :-
 	pretty_print(T,6).
 
 pretty_print(black([],[],[],[]),_) :- !.
@@ -919,8 +920,8 @@ is_rbtree(t(_,T)) :-
 % This code checks if a tree is ordered and a rbtree
 %
 %
-rbtree(black([],[],[],[])) :- !.
-rbtree(T) :-
+rbtree(t(_,black([],[],[],[]))) :- !.
+rbtree(t(_,T)) :-
 	catch(rbtree1(T),msg(S,Args),format(S,Args)).
 
 rbtree1(black(L,K,_,R)) :-
@@ -974,44 +975,44 @@ count(I,M,L) :-
 	I < M, I1 is I+1, count(I1,M,L).
 
 test_pos :-
-	new(1,a,T0),
+	rb_new(1,a,T0),
 	N = 10000,
 	build_ptree(2,N,T0,T),
 %	pretty_print(T),
 	rbtree(T),
 	clean_tree(1,N,T,_),
 	bclean_tree(N,1,T,_),
-	count(1,N,X), ( delete(T,X,TF) -> true ; abort ),
+	count(1,N,X), ( rb_delete(T,X,TF) -> true ; abort ),
 %	pretty_print(TF), 
 	rbtree(TF),
-	format("done ~d~n",[X]),
+%	format("done ~d~n",[X]),
 	fail.
 test_pos.
 
 build_ptree(X,X,T0,TF) :- !,
-	insert(T0,X,X,TF).
+	rb_insert(T0,X,X,TF).
 build_ptree(X1,X,T0,TF) :-
-	insert(T0,X1,X1,TI),
+	rb_insert(T0,X1,X1,TI),
 	X2 is X1+1,
 	build_ptree(X2,X,TI,TF).
 
 
 clean_tree(X,X,T0,TF) :- !,
-	delete(T0,X,TF),
+	rb_delete(T0,X,TF),
 	( rbtree(TF) -> true ; abort).
 clean_tree(X1,X,T0,TF) :-
-	delete(T0,X1,TI),
+	rb_delete(T0,X1,TI),
 	X2 is X1+1,
 	( rbtree(TI) -> true ; abort),
 	clean_tree(X2,X,TI,TF).
 
 bclean_tree(X,X,T0,TF) :- !,
-	format("cleaning ~d~n", [X]),
-	delete(T0,X,TF),
+%	format("cleaning ~d~n", [X]),
+	rb_delete(T0,X,TF),
 	( rbtree(TF) -> true ; abort).
 bclean_tree(X1,X,T0,TF) :-
-	format("cleaning ~d~n", [X1]),
-	delete(T0,X1,TI),
+%	format("cleaning ~d~n", [X1]),
+	rb_delete(T0,X1,TI),
 	X2 is X1-1,
 	( rbtree(TI) -> true ; abort),
 	bclean_tree(X2,X,TI,TF).
@@ -1020,26 +1021,26 @@ bclean_tree(X1,X,T0,TF) :-
 
 test_neg :-
 	Size = 10000,
-	new(-1,a,T0),
+	rb_new(-1,a,T0),
 	build_ntree(2,Size,T0,T),
 %	pretty_print(T),
 	rbtree(T),
 	MSize is -Size,
 	clean_tree(MSize,-1,T,_),
 	bclean_tree(-1,MSize,T,_),
-	count(1,Size,X), NX is -X, ( delete(T,NX,TF) -> true ; abort ),
+	count(1,Size,X), NX is -X, ( rb_delete(T,NX,TF) -> true ; abort ),
 %	pretty_print(TF), 
 	rbtree(TF),
-	format("done ~d~n",[X]),
+%	format("done ~d~n",[X]),
 	fail.
 test_neg.
 
 build_ntree(X,X,T0,TF) :- !,
 	X1 is -X,
-	insert(T0,X1,X1,TF).
+	rb_insert(T0,X1,X1,TF).
 build_ntree(X1,X,T0,TF) :-
 	NX1 is -X1,
-	insert(T0,NX1,NX1,TI),
+	rb_insert(T0,NX1,NX1,TI),
 	X2 is X1+1,
 	build_ntree(X2,X,TI,TF).
 
diff --git a/library/tries.yap b/library/tries.yap
index f177bfa4b..eabc22f8e 100644
--- a/library/tries.yap
+++ b/library/tries.yap
@@ -9,6 +9,7 @@
 		  trie_open/1,
 		  trie_close/1,
 		  trie_close_all/0,
+		  trie_empty/1,
 		  trie_mode/1,
 		  trie_put_entry/3,
 		  trie_check_entry/3,
@@ -20,6 +21,7 @@
 		  trie_intersect/2,
 		  trie_count_join/3,
 		  trie_count_intersect/3,
+		  trie_dup/2,
 		  trie_save/2,
 		  trie_load/2,
 		  trie_stats/4,
@@ -36,3 +38,12 @@
           ]).
 
 :- load_foreign_files([tries], [], init_tries).
+
+trie_empty(Trie) :-
+	trie_usage(Trie, 0, 0, _).
+
+trie_dup(Trie, CopyTrie) :-
+	trie_open(CopyTrie),
+	trie_join(CopyTrie, Trie).
+
+
diff --git a/library/wundgraphs.yap b/library/wundgraphs.yap
index 88fea8ea2..b5a067b82 100644
--- a/library/wundgraphs.yap
+++ b/library/wundgraphs.yap
@@ -26,6 +26,7 @@
 	    wdgraph_vertices/2 as wundgraph_vertices,
 	    wdgraph_del_vertices/3 as wundgraph_del_vertices,
 	    wdgraph_edge/4 as wundgraph_edge,
+	    wdgraph_symmetric_closure/2 as wdgraph_to_wundgraph,
 	    wdgraph_to_dgraph/2 as wundgraph_to_undgraph,
 	    dgraph_to_wdgraph/2 as undgraph_to_wundgraph,
 	    wdgraph_min_path/5 as wundgraph_min_path,
@@ -146,9 +147,6 @@ compact([K-_|Children], [K|CompactChildren]) :-
 	compact(Children, CompactChildren).
 
 
-wundgraph_del_vertices(G0, Vs, GF) :-
-	wdgraph_del_vertices(G0, Vs, GF).
-
 del_edge(_, [], []).
 del_edge(K1, [K-W|Children], NewChildren) :-
 	( K == K1 ->
@@ -161,17 +159,8 @@ del_edge(K1, [K-W|Children], NewChildren) :-
 	    NewChildren = [K-W|Children]
 	).
 
-wundgraph_edge(N1, N2, K, G) :-
-	wdgraph_edge(N1, N2, K, G).
-
-wdgraph_to_wundgraph(G, U) :-
-	wdgraph_symmetric_closure(G, U).
-
 wundgraph_to_wdgraph(G, G).
 
-wundgraph_to_undgraph(G1, G2) :-
-	    wdgraph_to_dgraph(G1, G2).
-
 
 % simplistic algorithm to build a minimal spanning tree.
 % Just sort edges and then walk over each one.