+ return true;
+}
+
+/*------------------------------------------------------------------.
+| Register a new relation between symbols as used. The first symbol |
+| has a greater precedence than the second one. |
+`------------------------------------------------------------------*/
+
+void
+register_precedence (graphid first, graphid snd)
+{
+ if (!prec_nodes)
+ init_prec_nodes ();
+ register_precedence_second_symbol (&(prec_nodes[first]->succ), snd);
+ register_precedence_second_symbol (&(prec_nodes[snd]->pred), first);
+}
+
+
+/*---------------------------------------.
+| Initialize association tracking table. |
+`---------------------------------------*/
+
+static void
+init_assoc (void)
+{
+ graphid i;
+ used_assoc = xcalloc(nsyms, sizeof(*used_assoc));
+ for (i = 0; i < nsyms; ++i)
+ used_assoc[i] = false;
+}
+
+/*------------------------------------------------------------------.
+| Test if the associativity for the symbols is defined and useless. |
+`------------------------------------------------------------------*/
+
+static inline bool
+is_assoc_useless (symbol *s)
+{
+ return s
+ && s->assoc != undef_assoc
+ && s->assoc != precedence_assoc
+ && !used_assoc[s->number];