a) Give the Dijkstra definition of a semaphore. What is a synchronization problem that the semaphore can solve but the simple lock cannot. b) The Dijkstra implementation of a semaphore is known to result in the problem of busy - wait. What is the problem with busy - wait and why is it undesirable? Provide pseudocode for the implementation of semaphore with and without the busy wait. In the case of implementation without busy - wait identify the points to which the wait is now limited