diff --git a/domains/value_domain.ml b/domains/value_domain.ml
index 0d2e342..d68edcb 100644
--- a/domains/value_domain.ml
+++ b/domains/value_domain.ml
@@ -158,8 +158,15 @@ module NonRelational (V : VALUE_DOMAIN) : DOMAIN = struct
 
 	let rec revise_HC4 tree mapenv newval = match tree with
 		| HC4_int_unary (uop, sub, abst) -> revise_HC4 sub mapenv (V.bwd_unary (get_abst sub) uop (V.meet abst newval))
-		| HC4_int_binary (bop, sub1, sub2, abst) -> let refined1, refined2 = V.bwd_binary (get_abst sub1) (get_abst sub2) bop (V.meet abst newval) in
-							    meet (revise_HC4 sub1 mapenv refined1) (revise_HC4 sub2 mapenv refined2)
+		| HC4_int_binary (bop, sub1, sub2, abst) -> let refined1, refined2 = V.bwd_binary (get_abst sub1) (get_abst sub2) bop (V.meet abst newval) in begin
+							    Format.printf "bwd_binary \"%a%s%a = %a\" -> %a, %a@ "
+								V.print (get_abst sub1)
+								(Cfg_printer.string_of_int_binary_op bop)
+								V.print (get_abst sub2)
+								V.print (V.meet abst newval)
+								V.print (refined1)
+								V.print (refined2);
+							    meet (revise_HC4 sub1 mapenv refined1) (revise_HC4 sub2 mapenv refined2) end
 		| HC4_int_var (v, abst)   -> E (VMap.add v (V.meet abst newval) mapenv)
 		| HC4_int_const (z,abst)  -> if( V.is_bottom (V.meet abst newval) ) then Bot else E mapenv
 		| HC4_int_rand (a,b,abst) -> if( V.is_bottom (V.meet abst newval) ) then Bot else E mapenv
@@ -174,6 +181,13 @@ module NonRelational (V : VALUE_DOMAIN) : DOMAIN = struct
 			| Bot -> Bot
 			| E mapenv ->	let hc4_1, hc4_2 = build_HC4 iexp1 mapenv, build_HC4 iexp2 mapenv in
 					let newval1, newval2 = V.compare (get_abst hc4_1) (get_abst hc4_2) cop in (
+					Format.printf "Refined comparison %a%s%a as %a%s%a@ "
+						V.print (get_abst hc4_1)
+						(Cfg_printer.string_of_compare_op cop)
+						V.print (get_abst hc4_2)
+						V.print newval1
+						(Cfg_printer.string_of_compare_op cop)
+						V.print newval2;
 					meet (revise_HC4 hc4_1 mapenv newval1) (revise_HC4 hc4_2 mapenv newval2) )
 
 	let guard env boolexp = guard_noneg env (rm_negations boolexp)