# Josef Bertrand

Date of Birth: 03/11/1822

Age: 78

Citizenship: France

**Background**

French mathematician who worked in the field of number theory, differential geometry, probability theory and thermodynamics.

Son of physics Alexander Jacques Francois Bertrand and his brother archaeologist Alexander Bertrand.

He was a professor of the Polytechnic School and the College of France. He was a member of the Paris Academy of Sciences and its permanent secretary for 26 years.

In 1845, put forward the hypothesis of the existence of at least one prime number between the numbers n and 2n-2 for every n> 3. This statement, called Bertrand postulate has been proven Chebyshev in 1850.

Bertrand also known paradoxes of the wording in the theory of probability and game theory.

In their theory of oligopoly economy has been revised, in particular, competition, Cournot model. He formulated model competition shows that the conclusions of Cournot are not met in terms of price competition. Equilibrium in this model is achieved at the level of perfect competition price.