Hacker Read

reacweb | karma 2123 | avg karma 2.37 · 2018-10-11 12:14:58

In https://en.wikipedia.org/wiki/Principia_Mathematica the conclusion that 1+1=2 appears only at page 379. It was a hard proof ;-)

taejo | karma 2300 | avg karma 1.86 · 2018-10-11 12:51:21+00:00

That's only true if you take a pretty arcane definition of 1 and 2, BTW. In modern axiomatizations of mathematics, as well as Peano's 19th-century axiomatization of arithmetic, the definitions of 1 and 2 are simpler, and the proofs that 1+1=2 take a couple lines.