A, B, C, and D are one-user computers. W, X, Y, and Z are students need to use the previous computers. a) When W, X, Y, Z use (hold) A, C, B, D respectively, then X, Y, Z, W request to use A, C, B, D,...

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Extracted text: A, B, C, and D are one-user computers. W, X, Y, and Z are students need to use the previous computers. a) When W, X, Y, Z use (hold) A, C, B, D respectively, then X, Y, Z, W request to use A, C, B, D, respectively. Draw the graph model, and comment whether there is a deadlock or not. b) Write a pseudo code using semaphores to manage the previous problem where every student should use the all single-user computers to finish.