diff --git a/Concurrent Systems/test/Untitled.md b/Concurrent Systems/test/Untitled.md
index 72d21aa..e84129b 100644
--- a/Concurrent Systems/test/Untitled.md	
+++ b/Concurrent Systems/test/Untitled.md	
@@ -1,34 +1,36 @@
 ```
-GLOB_MUTEX and R_MUTEX semaphores init. at 1
+GLOB_MUTEX, W_MUTEX, PR_MUTEX and R_MUTEX semaphores init. at 1
 R a shared register init. at 0
 
 begin_read() :=
-	PR_MUTEX.down()
+	PRR_MUTEX.down()
 	R_MUTEX.down()
 	R++ # currently active readers
 	if R = 1 then
-		W_MUTEX.down()
+		PRW_MUTEX.down()
 		GLOB_MUTEX.down()
 	R_MUTEX.up()
-	PR_MUTEX.up()
+	PRR_MUTEX.up()
 	return
 
 end_read() :=
 	R_MUTEX.down()
 	R--
-	if R = 0 then GLOB_MUTEX.up()
+	if R = 0 then
+		GLOB_MUTEX.up()
+		PRW_MUTEX.up()
 	R_MUTEX.up()
 	return
 
 begin_write() :=
-	W_MUTEX.down()
-	W_MUTEX.up()
-	PR_MUTEX.down()
+	PRR_MUTEX.down()
+	PRW_MUTEX.down()
+	PRW_MUTEX.up()
 	GLOB_MUTEX.down()
 	return
 
 end_write() :=
-	PR_MUTEX.up()
+	PRR_MUTEX.up()
 	GLOB_MUTEX.up()
 	return
 ```
\ No newline at end of file