For example he produced a beautiful solution to the functional equation f(f(x)) = ex which he published in 1950, and the deep understanding he achieved of the strange properties of manifolds without a countable basis of neighbourhoods between 1958 and 1964.
Halimbawa siya ginawa ng isang maganda solusyon sa functional equation f (f (x)) = e x na kung saan siya nai-publish sa 1950, at ang malalim-unawa siya makakamtan ng mga kakaibang pag-aari ng manifolds nang walang countable batayan ng neighbourhoods sa pagitan ng 1958 at 1964.