Frank p Ramsey frank ramsey, 1903~ 1930, British philosopher, mathematician and economist.
Yes, you are right. Ramsey died young at the age of 26.
One of Ramsey's important contributions to mathematics and logic is a combinatorial mathematics theory put forward by him in 1928, that is, Ramsey Theory named after him later.
This is a problem in combinatorial mathematics, Ramsey theorem, also known as Ramsey's second coloring theorem. Its intuitive description is:
In a group of more than six people, there must be three people who know each other or three people who don't know each other.
In other words:
In a group of more than six points on a plane, there must be three points connected to form a triangle or three points not connected to each other.
In other words:
In a complete 6-order graph, that is, 6 points and each point is connected with all other points, if there are two kinds of connecting lines, there must be a red triangle or a blue triangle.
Or:
So that at least k people among n people know each other or u people don't know each other, that is, r (k, u) = n. If k=3 and u=3, then the minimum value of n is 6.
As shown in the figure, how do you know that R (3,3) = 6 and R (4,4) =18? ...
The meaning of the friendship theorem is: in a group of not less than three people, if any two people happen to know each other only one person, then there is always one person in this group who is known by everyone.
From the perspective of graph theory, if each vertex of a graph happens to be adjacent to another vertex, then one vertex in this graph is adjacent to other vertices.
As shown in the figure, the graphic representation of friendship theorem is also called friendship diagram, windmill diagram or N fan diagram, and the bow pattern on the left is also called butterfly diagram.
There are several inferences from Ramsey's theorem, such as Vander Waals Deng's theorem, Hale-Jour's theorem, Schur's theorem and Rado's theorem.
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