سوال ۹۸ کنکور ارشد مهندسی کامپیوتر ۱۴۰۴

Concurrency is the general concept of multiple tasks (processes or threads) making progress during overlapping time intervals — they appear to run "at the same time," whether truly in parallel on multiple cores or interleaved by time-slicing on a single core. It is the umbrella concept; the other three terms are specific techniques that realize it.

Evaluate each option:

• Option 1 — False. Concurrency does not require multiprogramming. Concurrency can be achieved with multiple threads inside a single process, or by time-slicing, even without multiple programs resident in memory. Multiprogramming is one way to obtain concurrency, not a precondition for it.

• Option 2 — True. Multitasking is the concurrent execution of several tasks (processes) by interleaving them on the CPU over a period of time. It is precisely a form/type of concurrency.

• Option 3 — False. Multiprogramming (keeping several programs in main memory so the CPU is kept busy while one waits on I/O) is a specific technique, not identical to the broad concept of concurrency.

• Option 4 — True. Multithreading runs multiple threads of one process in overlapping time intervals — the textbook example of concurrency within a process. It is a type of concurrency.

Both option 2 and option 4 are correct statements: multitasking and multithreading are each genuine forms of concurrency. Accordingly the official answer key marks this question as multi-key, accepting either option 2 or option 4 as correct. We report option 4, since "threads of one process executing in overlapping time" is the canonical textbook instance of concurrency, but option 2 is equally valid.

Exam trick: Concurrency is the general idea; multitasking, multithreading and multiprogramming are mechanisms. "X is a type of concurrency" is true for multitasking and multithreading, but "X is the same as / required by concurrency" turns a technique into a definition and is false.