diff --git a/src/lib/clpb.pl b/src/lib/clpb.pl
index 0310e775..75a38282 100644
--- a/src/lib/clpb.pl
+++ b/src/lib/clpb.pl
@@ -49,17 +49,6 @@
    Compatibility predicates.
 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 
-group_pairs_by_key([], []).
-group_pairs_by_key([M-N|T0], [M-[N|TN]|T]) :-
-    same_key(M, T0, TN, T1),
-    group_pairs_by_key(T1, T).
-
-same_key(M0, [M-N|T0], [N|TN], T) :-
-    M0 == M,
-    !,
-    same_key(M, T0, TN, T).
-same_key(_, L, [], L).
-
 must_be(What, Term) :- must_be(What, unknown(Term)-1, Term).
 
 must_be(acyclic, Where, Term) :- !,
diff --git a/src/lib/clpz.pl b/src/lib/clpz.pl
index 3012af78..0c561b92 100644
--- a/src/lib/clpz.pl
+++ b/src/lib/clpz.pl
@@ -6985,10 +6985,6 @@ cumulative(Tasks, Options) :-
             resource_limit(Start, End, Tasks, Bss, L)
         ).
 
-min_(E, M0, M) :- M is min(E,M0).
-
-max_(E, M0, M) :- M is max(E,M0).
-
 /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    Trivial lower and upper bounds, assuming no gaps and not necessarily
    retaining the rectangular shape of each task.