一一

one by one / one after another

one / single / a (article) / as soon as / entire; whole; all; throughout / "one" radical in Chinese characters (Kangxi radical 1) / also pr. [yao1] for greater clarity when spelling out numbers digit by digit

bijective map (i.e. map between sets in math. that is one-to-one and onto) / one-to-one correspondence

one-to-one correspondence