09.Answer

For a thread pool of size 2, fork(fork(fork(x))) will deadlock, and so on. Another, perhaps more interesting example is fork(map2(fork(x), fork(y))). In this case, the outer task is submitted first and occupies a thread waiting for both fork(x) and fork(y). The fork(x) and fork(y) tasks are submitted and run in parallel, except that only one thread is available, resulting in deadlock.