Conjecture on primes (not mine=)

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    Conjecture Primes
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Discussion Overview

The discussion revolves around a conjecture related to the distribution of prime numbers, specifically examining the number of primes between the squares of integers and comparing it to the number of primes less than a linear expression. The scope includes theoretical aspects of number theory and conjectures regarding prime distribution.

Discussion Character

  • Debate/contested
  • Exploratory
  • Technical explanation

Main Points Raised

  • One participant presents a conjecture suggesting that the number of primes between \(x^2\) and \((x+1)^2\) is equal to the number of primes less than \(2x+1\) for \(x\) greater than 100.
  • Another participant argues that the conjecture is "obviously" false, noting that the two intervals considered are of the same length.
  • A different participant provides counterexamples to the conjecture, suggesting that it may be more accurate to state that the number of primes between \(x^2\) and \((x+1)^2\) is at most the number of primes below \(2x+1\), linking this to a conjecture by Hardy and Littlewood.
  • Discussion includes references to Legendre's Conjecture, which posits that there is at least one prime between \(n^2\) and \((n+1)^2\), and its unproven status as of 2009.
  • Participants explore the relationship between Legendre's Conjecture and Bertrand's Postulate, debating whether the latter can be used to prove the former.
  • Some participants express skepticism about the strength of Bertrand's Postulate in proving Legendre's Conjecture, with one stating that even the Riemann Hypothesis is too weak for such a proof.
  • There is a challenge posed to write a proof of Legendre's Conjecture conditional on the Riemann Hypothesis, with discussions about the growth of the prime counting function.

Areas of Agreement / Disagreement

Participants express disagreement regarding the validity of the initial conjecture, with some asserting it is false while others explore related conjectures and their implications. The discussion remains unresolved regarding the potential proof of Legendre's Conjecture using Bertrand's Postulate.

Contextual Notes

There are limitations in the discussion regarding the assumptions made about the conjectures and the relationships between them, as well as the lack of definitive proofs for the conjectures mentioned.

zetafunction
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i saw this conjecture on the web but do not know if is true

the number of primes between the expressions [tex]x^2[/tex] and [tex](x+1)^2[/tex]

for every x or at least for x bigger than 100

is equal to the Number of primes less than 2x+1 (the x are the same)
 
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Isn't this "obviously" false? The two intervals you consider are the same length...
 
zetafunction said:
i saw this conjecture on the web but do not know if is true

the number of primes between the expressions [tex]x^2[/tex] and [tex](x+1)^2[/tex]

for every x or at least for x bigger than 100

is equal to the Number of primes less than 2x+1 (the x are the same)

That conjecture is false (counterexamples: 101, 102, 103, ..., 10000, ...). Perhaps you mean
"the number of primes between x^2 and (x+1)^2 is at most the number of primes below 2x+1"
which is a special case of a conjecture of Hardy and Littlewood. Of course this conjecture is widely believed to be false, because it is incompatible with the prime tuple conjecture. I don't know if this special case is possible under the prime tuple conjecture.
 
Zetafunction may have confused Legendre's Conjecture, which states there is a prime number between n^2 and (n+1)^2. This remains unproven as of 2009.

They are conjectured tighter bounds, but this indicates just how little is know of this problem. http://en.wikipedia.org/wiki/Legendre's_conjecture
 
Last edited:
can't Legendre's Conjecture be proven using bertrand's postulate?
 
chhitiz said:
can't Legendre's Conjecture be proven using bertrand's postulate?

Bertrand's postulate can be used to show that there is a prime between p^2 and 2p^2. But (p+1)^2 = p^2 + 2p + 1 is smaller than 2p^2 (for p prime).
 
bertrand's postulate can show that there is a prime between (p+1)2/2 and (p+1)2. p2 is greater than (p+1)2/2 after 2.
 
well, somebody please tell me if i was correct. can bertrand's postulate be used to prove legendre's conjecture?
 
chhitiz said:
well, somebody please tell me if i was correct. can bertrand's postulate be used to prove legendre's conjecture?

No. Bertrand's postulate isn't nearly strong enough. Even the Riemann hypothesis is too weak!
 
  • #10
chhitiz said:
well, somebody please tell me if i was correct. can bertrand's postulate be used to prove legendre's conjecture?

What CR said is correct. How do I know? Trust me I've tried it.

Although saying the RH is too weak is a bold statement. I think with the RH proved, Legendre's won't put up much of a fight.

The thing about conjectures such as Legendre's is that they are similar to FLT, nearly an unlimited amount of conjectures similar to it can be made: Just from Legendre's conjecture I can make a bunch of other conjectures similar to it without any proofs (as of yet, especially without the RH).
 
  • #11
camilus said:
Although saying the RH is too weak is a bold statement. I think with the RH proved, Legendre's won't put up much of a fight.

I challenge you to write a proof of Legendre's conjecture conditional on the RH.
 
  • #12
CRGreathouse said:
I challenge you to write a proof of Legendre's conjecture conditional on the RH.

I don't even think its necessary, but how would you say the prime counting function grows, linear, logarithmic, exponential..?
 

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