![]() to understand as an undefined term. In any case, it is imposible to make infinity as a mathematical subject. ![]() infinity itself. ![]() postulate perfectly. But he relied on his own supposition about infinity itself. Also he judged the geometry stands up by insight without evidence. ![]() choosing a certain metric. But to give metric sounds intentional and not inevitable. ![]() geometry following Klein's Erlangen Programme. Be that as it may, we still feel something kile a conjuring trick. ![]() theory. ![]() has the hyperbolic geometry. |