diff --git a/src/twa/bdddict.cc b/src/twa/bdddict.cc
index 0f23a6d5e..6cc9e63ae 100644
--- a/src/twa/bdddict.cc
+++ b/src/twa/bdddict.cc
@@ -155,43 +155,6 @@ namespace spot
     return num;
   }
 
-  void
-  bdd_dict::register_acceptance_variables(bdd f, const void* for_me)
-  {
-    if (f == bddtrue || f == bddfalse)
-      return;
-
-    int v = bdd_var(f);
-    assert(unsigned(v) < bdd_map.size());
-    bdd_info& i = bdd_map[v];
-    assert(i.type == acc);
-    i.refs.insert(for_me);
-
-    register_acceptance_variables(bdd_high(f), for_me);
-    register_acceptance_variables(bdd_low(f), for_me);
-  }
-
-  formula
-  bdd_dict::oneacc_to_formula(int var) const
-  {
-    assert(unsigned(var) < bdd_map.size());
-    const bdd_info& i = bdd_map[var];
-    assert(i.type == acc);
-    return i.f;
-  }
-
-  formula
-  bdd_dict::oneacc_to_formula(bdd oneacc) const
-  {
-    assert(oneacc != bddfalse);
-    while (bdd_high(oneacc) == bddfalse)
-      {
-	oneacc = bdd_low(oneacc);
-	assert(oneacc != bddfalse);
-      }
-    return oneacc_to_formula(bdd_var(oneacc));
-  }
-
   int
   bdd_dict::register_anonymous_variables(int n, const void* for_me)
   {
@@ -313,17 +276,6 @@ namespace spot
     priv_->free_anonymous_list_of.erase(me);
   }
 
-  void
-  bdd_dict::unregister_all_typed_variables(var_type type, const void* me)
-  {
-    unsigned s = bdd_map.size();
-    for (unsigned i = 0; i < s; ++i)
-      if (bdd_map[i].type == type)
-	unregister_variable(i, me);
-    if (type == anon)
-      priv_->free_anonymous_list_of.erase(me);
-  }
-
   std::ostream&
   bdd_dict::dump(std::ostream& os) const
   {
diff --git a/src/twa/bdddict.hh b/src/twa/bdddict.hh
index 53ccc94a4..39f741e8a 100644
--- a/src/twa/bdddict.hh
+++ b/src/twa/bdddict.hh
@@ -143,44 +143,6 @@ namespace spot
     }
     /// @}
 
-    /// \brief Register BDD variables as acceptance variables.
-    ///
-    /// Register all variables occurring in \a f as acceptance variables
-    /// used by \a for_me.  This assumes that these acceptance variables
-    /// are already known from the dictionary (i.e., they have already
-    /// been registered by register_acceptance_variable() for another
-    /// automaton).
-    /// @{
-    void register_acceptance_variables(bdd f, const void* for_me);
-
-    template <typename T>
-    void register_acceptance_variables(bdd f, std::shared_ptr<T> for_me)
-    {
-      register_acceptance_variables(f, for_me.get());
-    }
-    /// @}
-
-    /// \brief Convert one acceptance condition into the associated
-    /// formula.
-    ///
-    /// This version accepts a conjunction of Acc variables, in which
-    /// only one must be positive.  This positive variable will be
-    /// converted back into the associated formula.
-    ///
-    /// The returned formula is not cloned, and is valid until the BDD
-    /// variable used in \a oneacc are unregistered.
-    formula oneacc_to_formula(bdd oneacc) const;
-
-    /// \brief Convert one acceptance condition into the associated
-    /// formula.
-    ///
-    /// This version takes the number of a BDD variable that must has
-    /// been returned by a call to register_acceptance_variable().
-    ///
-    /// The returned formula is not cloned, and is valid until the BDD
-    /// variable \a var is unregistered.
-    formula oneacc_to_formula(int var) const;
-
     /// \brief Register anonymous BDD variables.
     ///
     /// Return (and maybe allocate) \a n consecutive BDD variables which
@@ -267,18 +229,6 @@ namespace spot
     /// Usually called in the destructor if \a me.
     void unregister_all_my_variables(const void* me);
 
-    /// \brief Release all variables of a given type, used by an
-    /// object.
-    /// @{
-    void unregister_all_typed_variables(var_type type, const void* me);
-
-    template <typename T>
-    void unregister_all_typed_variables(var_type type, std::shared_ptr<T> me)
-    {
-      unregister_all_typed_variables(type, me.get());
-    }
-    /// @}
-
     /// \brief Release a variable used by \a me.
     /// @{
     void unregister_variable(int var, const void* me);