diff --git a/AlgebraicDataflowArchitectureModel/models/POS2.model b/AlgebraicDataflowArchitectureModel/models/POS2.model
index 442079b..6988d7e 100644
--- a/AlgebraicDataflowArchitectureModel/models/POS2.model
+++ b/AlgebraicDataflowArchitectureModel/models/POS2.model
@@ -1,5 +1,5 @@
 channel CIO {
-	out payment(p:Int, purchase(x)) == x
+	out payment(p:Int, purchase(x:Int)) == x
 }
 
 channel C1 {
@@ -10,9 +10,5 @@
 channel C2 {
 	in payment(p1, update2(z)) == z
 	out history(h:List, update2(z)) == cons(z, h)
-}
-
-channel C3 {
-	in history(h, update3(u)) == cons(u, h)
-	out total(t:Int, update3(u)) == u + t
+	out total(t:Int, update3(z)) == z + t
 }
\ No newline at end of file