Theorem 10: Prime Counting Function and Loglog x

In summary, the conversation discusses theorem 10 in Hardy's book on number theory, which states that pi[x] is greater than or equal to loglog x. The book's arguments are compact and the speaker is seeking help in understanding how p_{n}<2^{2^n} was derived. The rest of the theorem follows from the fact that pi(x) is increasing and \pi(p_n)=n, which is not explicitly mentioned in the book. The speaker also mentions Bertrand's postulate, but it is not necessary for this proof as the bound of p_n is weaker. The proof is simpler and can be adapted from Euclid's proof that there are infinitely many primes.
  • #1
AlbertEinstein
113
1
I am going through Hardy's book on number theory.The following theorem I do not understand.

theorem 10: pi[x] >= loglog x
where pi[x] is the prime counting function
and >= stands for greater than or equal to

The arguments written in the book are very compact.please help .
 
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  • #2
Do you follow any of it?

Do you understand how they derived [tex]p_{n}<2^{2^n}[/tex] ?

this is an important step. The rest just follows from pi(x) being increasing, and also [tex]\pi(p_n)=n[/tex] which they use but don't explicitly mention.
 
  • #3
Bertrand's postulate?
 
  • #4
Nope! the bound of p_n above is much weaker than Bertrand's will give you. It's correspondingly simpler to prove though, it follows from a slight adaptation of Euclid's proof there are infinitely many primes (in case anyone who hasn't seen it wants to give it a stab)
 

1. What is Theorem 10: Prime Counting Function and Loglog x?

Theorem 10 is a mathematical theorem that relates the prime counting function π(x) to the logarithmic integral function li(x) through the use of the loglog x function. It provides a more efficient way to approximate the number of prime numbers less than a given number x.

2. How is Theorem 10 used in mathematics?

Theorem 10 is used in number theory to estimate the number of prime numbers less than a given number x. It is also used in the Riemann hypothesis to provide a tighter bound on the error term in the prime number theorem.

3. Who discovered Theorem 10?

Theorem 10 was discovered by the mathematician Hans von Mangoldt in 1895. He was a German mathematician known for his work in number theory and the Riemann hypothesis.

4. What is the significance of Theorem 10?

Theorem 10 has significant implications in the study of prime numbers and the distribution of primes. It provides a more accurate and efficient way to approximate the number of prime numbers, which has important applications in cryptography and number theory.

5. Are there any limitations to Theorem 10?

Like any mathematical theorem, Theorem 10 has its limitations. It is based on the Riemann hypothesis, which has not been proven yet, so the accuracy of its approximation is dependent on the validity of the Riemann hypothesis. Additionally, it only provides an asymptotic approximation and may not give an exact number for the number of prime numbers less than a given number x.

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