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A proof of proof by infinite descent

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Re: A proof of proof by infinite descent

#3
post #2

> I imagine that one could also prove that √−1 is not rational I feel like this was a marvellous joke but I can’t prove it.

You'd be surprised at the number of things that appear to be self-evidently true that turn out to depend on tacit assumptions. For example, is 7 prime? Not if you're doing modular arithmetic.

Re: A proof of proof by infinite descent

#4
post #3
post #2

> I imagine that one could also prove that √−1 is not rational I feel like this was a marvellous joke but I can’t prove it.

You'd be surprised at the number of things that appear to be self-evidently true that turn out to depend on tacit assumptions. For example, is 7 prime? Not if you're doing modular arithmetic.

i think they were joking, but i can't prove it

Re: A proof of proof by infinite descent

#5
post #3
post #2

> I imagine that one could also prove that √−1 is not rational I feel like this was a marvellous joke but I can’t prove it.

You'd be surprised at the number of things that appear to be self-evidently true that turn out to depend on tacit assumptions. For example, is 7 prime? Not if you're doing modular arithmetic.

It's also independently pretty tedious to explain that 7 is prime to a proof checker.

Re: A proof of proof by infinite descent

#6
post #3

Earlier quoted context omitted.

You'd be surprised at the number of things that appear to be self-evidently true that turn out to depend on tacit assumptions. For example, is 7 prime? Not if you're doing modular arithmetic.

It's also independently pretty tedious to explain that 7 is prime to a proof checker.

Is it? You can tell the checker about the remainder of division by 2 to 6.

Re: A proof of proof by infinite descent

#8
post #3
post #2

> I imagine that one could also prove that √−1 is not rational I feel like this was a marvellous joke but I can’t prove it.

You'd be surprised at the number of things that appear to be self-evidently true that turn out to depend on tacit assumptions. For example, is 7 prime? Not if you're doing modular arithmetic.

It's a joke about `i` being imaginary.

Re: A proof of proof by infinite descent

#9
post #3

Earlier quoted context omitted.

You'd be surprised at the number of things that appear to be self-evidently true that turn out to depend on tacit assumptions. For example, is 7 prime? Not if you're doing modular arithmetic.

It's a joke about `i` being imaginary.

yes the joke is on i

Re: A proof of proof by infinite descent

#10
post #3

Earlier quoted context omitted.

You'd be surprised at the number of things that appear to be self-evidently true that turn out to depend on tacit assumptions. For example, is 7 prime? Not if you're doing modular arithmetic.

It's also independently pretty tedious to explain that 7 is prime to a proof checker.

The proof is not too bad in Lean4. I'm nothing special and I've got it down to 9 lines. But, maybe that is considered pretty tedious vs. what expectations one might have. In any case, it is an exercise in Heather MacBeth's free book: The Mechanics of Proof,

https://hrmacbeth.github.io/math2001/04_Proofs_with_Structur...

btw, that book is a lot of fun to work through.

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