# 可怕的关系度3：质变的一个界限

P对NP”的研究结果暗示：

（1）像筛法证明哥德巴赫猜想：1+2和1+3、2+2类似；但1+1可能会有质的结构变化。
（2）2SAT是P；3SAT是NPC。

（3）连沙可夫斯基 (A. N. Sharkovsky) 都怕3：出现3周期就混沌了。
（4）4次代数方程的根能用系数表示出；5次方程则不行。

（5）3点一定是平面的；4点一般则是立体的。

（6）2体问题是简单的；3体问题就复杂了。
……

[1] 中国科学报2013-7-19，张益唐：孤独的数学家
http://news.sciencenet.cn/htmlnews/2013/7/280149.shtm
[2] 中国科学报2013-5-27，张益唐破译孪生素数猜想：无名之辈的逆袭
http://news.sciencenet.cn/htmlnews/2013/5/278319.shtm

[3] Hilbert problems - Encyclopedia of Mathematics
http://www.encyclopediaofmath.org/index.php/Hilbert_problems
[4] The Millennium Prize Problems
http://www.claymath.org/millennium/
[5] 希尔伯特的23个问题
http://en.wikipedia.org/wiki/Hilbert%27s_problems
[6] Graph, planar  - Encyclopedia of Mathematics
http://www.encyclopediaofmath.org/index.php/Graph,_planar
[5] Sharkovskii's theorem
http://en.wikipedia.org/wiki/Sharkovskii's_theorem
[6] Galois theory - Encyclopedia of Mathematics
http://www.encyclopediaofmath.org/index.php/Galois_theory

[1] Twins - Encyclopedia of Mathematics
Two primes the difference between which is 2.
http://www.encyclopediaofmath.org/index.php/Twins

[2] The twin prime conjecture:
There are infinitely many primes p such that p + 2 is also prime.
http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Twin_prime_conjecture.html

[3]It is conjectured that there are an infinite number of twin primes (this is one form of the twin prime conjecture)
http://mathworld.wolfram.com/TwinPrimes.html

http://blog.sciencenet.cn/blog-107667-710358.html

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