Processes holding resources can request new resources. No preemption condition. Circular wait condition. Designing algorithms that prevent deadlock involves preventing one or more of the above conditions. When considering deadlock, it is useful to draw a resource graph that shows processes and resources.
Conservative policies deny resources even when they are available.
However, they reduce the likelyhood of deadlock at the expense of reduced concurrency Liberal policies allocate resources when they are available at the risk of entering a deadlock state later. Dining Philosophers Problem Classic problem to demonstrate both deadlock and starvation. Five philosophers seated around a table with ten chopsticks and five rice bowls. Need two chopsticks to eat rice. Philosophers alternate between thinking and eating.