Jim Simons · Oct 15

For me, this illustrates the importance of counterexamples and non-examples in understanding mathematics. Nobody who had ever met e^(-1/x²) would make this mistake even if they have misremembered what the condition really is.

Robert Low · Oct 15

Somebody needs to learn about the difference between C^\infty and analytic.

Susan Whitehouse · Oct 15

Do you think they actually believe that it converges for all values of x, or do you think there's confusion around the meaning of the word 'valid'?