diff --git a/src/lib/CoAlgFormula.ml b/src/lib/CoAlgFormula.ml
index 3be60411365dfa67076bbe1c0270a1881bd0c1cf..5b4435946e9799eb6bef7fb5b4829e0a0956b448 100644
--- a/src/lib/CoAlgFormula.ml
+++ b/src/lib/CoAlgFormula.ml
@@ -61,6 +61,12 @@ type formula =
   | MU of formula * formula
   | NU of formula * formula
   | VAR of string
+  | AF of formula
+  | EF of formula
+  | AG of formula
+  | EG of formula
+  | AU of formula * formula
+  | EU of formula * formula
 
 exception ConversionException of formula
 
diff --git a/src/lib/CoAlgFormula.mli b/src/lib/CoAlgFormula.mli
index c912ef2b7aa11851093b9571af3676529347f0b8..3397ba44a4e8e3ad73e0e00a75786a3eb50037d3 100644
--- a/src/lib/CoAlgFormula.mli
+++ b/src/lib/CoAlgFormula.mli
@@ -44,6 +44,12 @@ type formula =
   | MU of formula * formula
   | NU of formula * formula
   | VAR of string
+  | AF of formula
+  | EF of formula
+  | AG of formula
+  | EG of formula
+  | AU of formula * formula
+  | EU of formula * formula
 
 exception ConversionException of formula