Not all even numbers greater than 2 can be represented as two prime numbers. This question was put forward by the German mathematician C Goldbach (1690- 1764) in a letter to the great mathematician Euler on June 7th, 742, so it is called Goldbach conjecture. On June 30th of the same year, Euler replied that this conjecture may be true, but he could not prove it. Since then, this mathematical problem has attracted the attention of almost all mathematicians. Goldbach conjecture has therefore become an unattainable "pearl" in the crown of mathematics. "In contemporary languages, Goldbach conjecture has two contents, the first part is called odd conjecture, and the second part is called even conjecture. Odd number conjecture points out that any odd number greater than or equal to 7 is the sum of three prime numbers. Even conjecture means that even numbers greater than or equal to 4 must be the sum of two prime numbers. " (Quoted from Goldbach conjecture and Pan Chengdong) Goldbach conjecture seems simple, but it is not easy to prove, which has become a famous problem in mathematics. In 18 and 19 centuries, all number theory experts did not make substantial progress in proving this conjecture until the 20th century. It is directly proved that Goldbach's conjecture is not valid, and people adopt "circuitous tactics", that is, first consider expressing even numbers as the sum of two numbers, and each number is the product of several prime numbers. If the proposition "every big even number can be expressed as the sum of a number with no more than one prime factor and a number with no more than b prime factors" is recorded as "a+b", then the Coriolis conjecture is to prove that "1+ 1" holds. 1900, Hilbert, the greatest mathematician in the 20th century, listed Goldbach conjecture as one of the 23 mathematical problems at the International Mathematical Congress. Since then, mathematicians in the 20th century have "joined hands" to attack the world's "Goldbach conjecture" fortress, and finally achieved brilliant results. In the 1920s, people began to approach it. 1920, the Norwegian mathematician Bujue proved by an ancient screening method that every even number greater than 6 can be expressed as (9+9). This method of narrowing the encirclement is very effective, so scientists gradually reduce the number of prime factors of each number from (99) until each number is a prime number, thus proving Goldbach's conjecture. The main methods used by mathematicians in the 20th century to study Goldbach's conjecture are screening method, circle method, density method, triangle method and so on. The way to solve this conjecture, like "narrowing the encirclement", is gradually approaching the final result. Thanks to Chen Jingrun's contribution, mankind is only one step away from the final result of Goldbach's conjecture "1+ 1". But in order to achieve this last step, it may take a long exploration process. Many mathematicians believe that to prove "1+ 1", new mathematical methods must be created, and the previous methods are probably impossible. 1in the spring of 966, Chen Jingrun announced to the world that he had reached the best result about Goldbach's conjecture (1+2), that is, any even number large enough can be expressed as the sum of two numbers, one of which is a prime number and the other is the product of no more than two prime numbers. 1966, Chen Jingrun's paper was published in 17 issue of Science Bulletin. (The original is more than 200 pages, which is jumbled. ) 1972, Chen Jingrun improved the ancient screening method, proved Goldbach's conjecture completely and beautifully (1+2), and improved the paper of 1966. 1973 China Science Journal officially published Chen Jingrun's paper "A big even number is the sum of the products of a prime number and no more than two prime numbers". The title of this paper is the same as Chen Jingrun's paper 1966 published in Science Bulletin in June, but the content is brand-new and the article is concise. The typesetting of this paper is also quite laborious. Because there are many mathematical formulas and symbols in the paper, and many of them are nested in multiple layers, it is very difficult to spell them out. The printing house of the Academy of Sciences sent Ou Guangdi, a senior compositor, to operate for a whole week. Therefore, it is only posted at the beginning of Mr. Chen Jingrun's paper that P_x( 1, 2) is the number of prime numbers P suitable for the following conditions: x-p=p_ 1 or x-p=(p_2)*(p_3), where p_ 1, p_2. Life CX = {∏ p | x, p 2} (p-1)/(p-2) {∏ p 2} (1-1) 2. Chen Jingrun's proof is so long that people who are not majoring in number theory generally can't understand it. See Pan Chengdong and Pan Chengbiao's Goldbach Conjecture, Beijing: Science Press, 198 1. This book is very old, it should be out of print now, and it can be found in a relatively large library. There are many FTP in the education network. Public download address:/files/4c76D4296488476cb4b579b3cb2a21. Gain-Bandwidth Product (short for gain-bandwidth product)