diff --git a/ChangeLog b/ChangeLog
index 620ee0032..6c503c306 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2003-06-24  Alexandre Duret-Lutz  <aduret@src.lip6.fr>
+
+	* src/ltlvisit/nenoform.cc (negative_normal_form): New const variant.
+	* src/ltlvisit/nenoform.hh (negative_normal_form): New const variant.
+	* src/ltlvisit/lunabbrev.cc (unabbreviate_logic): New const variant.
+	* src/ltlvisit/lunabbrev.hh (unabbreviate_logic): New const variant.
+	* src/ltlvisit/tunabbrev.cc (unabbreviate_ltl): New const variant.
+	* src/ltlvisit/tunabbrev.hh (unabbreviate_ltl): New const variant.
+
 2003-06-23  Alexandre Duret-Lutz  <aduret@src.lip6.fr>
 
 	Switch from "promises" to "accepting set".  Fix the definitions
diff --git a/src/ltlvisit/lunabbrev.cc b/src/ltlvisit/lunabbrev.cc
index 3676113df..0a8252229 100644
--- a/src/ltlvisit/lunabbrev.cc
+++ b/src/ltlvisit/lunabbrev.cc
@@ -73,5 +73,10 @@ namespace spot
       return v.result();
     }
 
+    const formula*
+    unabbreviate_logic(const formula* f)
+    {
+      return unabbreviate_logic(const_cast<formula*>(f));
+    }
   }
 }
diff --git a/src/ltlvisit/lunabbrev.hh b/src/ltlvisit/lunabbrev.hh
index e24286e0b..3ce95eb7c 100644
--- a/src/ltlvisit/lunabbrev.hh
+++ b/src/ltlvisit/lunabbrev.hh
@@ -38,6 +38,10 @@ namespace spot
     /// binop::Equals, and binop::Xor, using only unop::Not, multop::Or,
     /// and multop::And.
     formula* unabbreviate_logic(formula* f);
+    /// \brief Clone rewrite a formula to remove most of the abbreviated
+    /// logical operators.
+    const formula* unabbreviate_logic(const formula* f);
+
   }
 }
 
diff --git a/src/ltlvisit/nenoform.cc b/src/ltlvisit/nenoform.cc
index e8d18dfb8..5d02bb33f 100644
--- a/src/ltlvisit/nenoform.cc
+++ b/src/ltlvisit/nenoform.cc
@@ -174,5 +174,11 @@ namespace spot
       f->accept(v);
       return v.result();
     }
+
+    const formula*
+    negative_normal_form(const formula* f)
+    {
+      return negative_normal_form(const_cast<formula*>(f));
+    }
   }
 }
diff --git a/src/ltlvisit/nenoform.hh b/src/ltlvisit/nenoform.hh
index 2290fc30e..b35743a31 100644
--- a/src/ltlvisit/nenoform.hh
+++ b/src/ltlvisit/nenoform.hh
@@ -23,6 +23,8 @@ namespace spot
     /// after spot::ltl::negative_normal_form would likely produce a
     /// formula which is not in negative normal form.)
     formula* negative_normal_form(formula* f, bool negated = false);
+    /// \brief Build the negative normal form of \a f.
+    const formula* negative_normal_form(const formula* f);
   }
 }
 
diff --git a/src/ltlvisit/tunabbrev.cc b/src/ltlvisit/tunabbrev.cc
index eb1c23a98..eec8a0db8 100644
--- a/src/ltlvisit/tunabbrev.cc
+++ b/src/ltlvisit/tunabbrev.cc
@@ -49,5 +49,11 @@ namespace spot
       return v.result();
     }
 
+    const formula*
+    unabbreviate_ltl(const formula* f)
+    {
+      return unabbreviate_ltl(const_cast<formula*>(f));
+    }
+
   }
 }
diff --git a/src/ltlvisit/tunabbrev.hh b/src/ltlvisit/tunabbrev.hh
index 6854d81cc..813077180 100644
--- a/src/ltlvisit/tunabbrev.hh
+++ b/src/ltlvisit/tunabbrev.hh
@@ -42,6 +42,9 @@ namespace spot
     /// This will also rewrite unary operators such as unop::F,
     /// and unop::G, using only binop::U, and binop::R.
     formula* unabbreviate_ltl(formula* f);
+    /// \brief Clone and rewrite a formula to remove most of the
+    /// abbreviated LTL and logical operators.
+    const formula* unabbreviate_ltl(const formula* f);
   }
 }