[ColinWright]

I wonder if he got the idea from Hardy, who before undertaking a journey on a very small boat sent a postcard saying he had proved the Riemann Hypothesis:

Hardy stayed in Denmark with Bohr until the very end of the summer vacation, and when he was obliged to return to England to start his lectures there was only a very small boat available…. The North Sea can be pretty rough, and the probability that such a small boat would sink was not exactly zero. Still, Hardy took the boat, but sent a postcard to Bohr: “I proved the Riemann Hypothesis. G.H. Hardy.” If the boat sinks and Hardy drowns, everybody must believe that he has proved the Riemann Hypothesis. Yet God would not let Hardy have such a great honor and so He will not let the boat sink.

-- https://home.cc.umanitoba.ca/~mcleod/Riemann/Hardy.html

[anthony__j]

haha, that's pretty clever. makes you wonder if fermat was doing a similar prank with his margins

[ColinWright]

It's generally believed that Fermat thought he had a proof, but probably almost immediately remembered that not everything is a Unique Factorization Domain, so the "obvious proof" fails. Then he didn't bother returning to correct the error.

So no, probably not.

(+) I should go and learn more about the specifics of this to make sure I'm relating it correctly.

EDIT: (++) OK, here's what I was thinking about:

https://math.stackexchange.com/questions/953462/what-was-lam...

EDIT2: (++) Second link with similar details:

https://math.stackexchange.com/questions/324740/fermats-proo...

[ducttapecrown]

I just recently learned that the note in Fermat's margin was published posthumously by his son! So Fermat never necessarily publicly claimed to have a proof. So I would imagine you're absolutely correct.