There are some conjectures which most leading experts believe in albeit no one can prove it yet. For example: $\mathcal{P} \neq \mathcal{NP}$, the Riemann hypothesis or the Collatz conjecture.

My question is whether there is a set of such conjectures which cannot all be true, eg. is a statement such as "Either $\mathcal{P} = \mathcal{NP}$ or the Riemann hypothesis is wrong" true?


In an early instance of a computer-assisted proof, Douglas Hensley and Ian Richards (Primes in Intervals, Acta Arithmetica 25 (1974), 375-391) proved that two conjectures of Hardy and Littlewood about prime numbers, the first Hardy-Littlewood conjecture (the prime $k$-tuples conjecture, a generalization of the twin primes conjecture) and the second Hardy-Littlewood conjecture (that $\pi(x+y)\le\pi(x)+\pi(y)$), can not both be true. As a result of this work of Hensley and Richards, the second Hardy-Littlewood conjecture has fallen out of favor.

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    $\begingroup$ I love answers where half the text is blue. $\endgroup$
    – user856
    Jan 6 '15 at 6:56
  • $\begingroup$ I love comments with a brown-red number in front. $\endgroup$ Oct 1 at 19:02

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