October 2021

Bertrand’s Postulate

For every number greater than 1, there is at least one prime number between the number and its double.

Bertrand’s postulate states that there is at least one prime number p, such that n < p < 2n.

Pictorial representation

This Postulate was first proposed by Bertrand in 1845.

However, Bertrand did check that his conjecture was true up to 3 million.

It was first proved in 1850 by Chebyshev so is also called the Bertrand-Chebyshev Theorem.

Chebyshev on a 2021 stamp of Russia

The Indian Mathematician Ramanujan, who was not aware of Chebyshev’s proof, came up with an easier proof on 1919.

In 1932, a Hungarian Mathematician, Paul Erdos, came with another different proof.

Bertrand Russell

Bertrand Russell (18 – 05 – 1872 to 02 – 02 -1970), a famous British mathematician.

In his autobiography he mentioned

It was my desire to know more about Mathematics that kept me away from suicide

Bertrand Russell
Bertrand Russell on 1972 stamp of India

Goldbach’s Conjecture

Goldbach’s conjecture is one of the oldest unsolved problems in mathematics.


Any even number greater than 2 can be written as the sum of two prime number.

Every odd whole number greater than 5 can be written as the sum of three primes. 

Goldbach’s conjectures

Goldbach, a Prussian mathematician(1690-1764)

On 7 June 1742, Goldbach wrote a letter to the mathematician Euler in which he proposed the conjectures he found.

Euler responded back on 30 June 1742 as

Every integer greater than 2 is a sum of two primes, I regard this as a completely certain theorem, although I cannot prove it.

Euler

Though the Goldbach’s conjecture looks simple to understand, it has not yet been proved.

In the modern times, the conjectures proposed by Goldbach is identified as weak or strong Goldbach conjecture.

STRONG GOLDBACH CONJECTURE

Any even whole number greater than 2 can be written as the sum of two prime number.

WEAK GOLDBACH CONJECTURE

Every odd whole number greater than 5 can be written as the sum of three primes. 

In 2013, Harold Helfgott, a Peruvian mathematician released two papers claiming the proof of Goldbach weak conjecture and The proof was accepted for publication in the Annals of mathematics series in 2015, and has been undergoing further review and revisions.

In March 2000 the publishers of the book ‘Uncle Petros and Goldbach’s conjecture (Bloomberg in the USA and Faber and Faber in the UK) offered a prize of one million dollars for anyone who could prove the Goldbach’s conjecture

Any even whole number greater than 2 can be written as the sum of two prime number.

The prize was kept open for two years, but nobody claimed it.