diff --git a/src/misc/util/utilTruth.h b/src/misc/util/utilTruth.h
index 124af310a..7eec26c9e 100644
--- a/src/misc/util/utilTruth.h
+++ b/src/misc/util/utilTruth.h
@@ -982,6 +982,31 @@ static inline void Abc_TtFlip( word * pTruth, int nWords, int iVar )
     }    
 }
 
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline word Abc_Tt6Permute_rec( word t, int * pPerm, int nVars )
+{
+    word uRes0, uRes1; int Var;
+    if (  t == 0 ) return 0;
+    if ( ~t == 0 ) return ~(word)0;
+    for ( Var = nVars-1; Var >= 0; Var-- )
+        if ( Abc_Tt6HasVar( t, Var ) )
+             break;
+    assert( Var >= 0 );
+    uRes0 = Abc_Tt6Permute_rec( Abc_Tt6Cofactor0(t, Var), pPerm, Var );
+    uRes1 = Abc_Tt6Permute_rec( Abc_Tt6Cofactor1(t, Var), pPerm, Var );
+    return (uRes0 & s_Truths6Neg[pPerm[Var]]) | (uRes1 & s_Truths6[pPerm[Var]]);
+}
+
 /**Function*************************************************************
 
   Synopsis    []