Update According to Review Comments #397

Resubmit of updates

mutex/README.md

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+---
+layout: pattern
+title: Mutex
+folder: mutex
+permalink: /patterns/mutex/
+categories: Lock
+tags: 
+ - Java
+ - Difficulty-Beginner
+---
+
+## Also known as
+Mutual Exclusion Lock
+Binary Semaphore
+
+## Intent
+Create a lock which only allows a single thread to access a resource at any one instant.
+
+![alt text](./etc/mutex.png "Mutex")
+
+## Applicability
+Use a Mutex when
+
+* you need to prevent two threads accessing a critical section at the same time
+* concurrent access to a resource could lead to a race condition 
+
+## Credits
+
+* [Lock (computer science)] (http://en.wikipedia.org/wiki/Lock_(computer_science))
+* [Semaphores] (http://tutorials.jenkov.com/java-concurrency/semaphores.html)