解释 Vinay Deolalikar 的证明 P != NP

发布于 2024-09-13 14:08:01 字数 1455 浏览 4 评论 0原文

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傾旎 2024-09-20 14:08:01

我只浏览了这篇论文,但这里是所有内容如何结合在一起的粗略总结。

从论文第86页开始。

...多项式时间
算法成功通过先后
将问题“分解”为
连接到的较小的子问题
彼此有条件地
独立。因此,多项式
时间算法无法解决
体制中的问题,其中的障碍
顺序与底层相同
问题实例需要同时进行
分辨率。

论文的其他部分表明某些 NP 问题不能以这种方式分解。因此 NP/= P

本文的大部分内容都花在定义条件独立性并证明这两点上。

I've only scanned through the paper, but here's a rough summary of how it all hangs together.

From page 86 of the paper.

... polynomial time
algorithms succeed by successively
“breaking up” the problem into
smaller subproblems that are joined to
each other through conditional
independence. Consequently, polynomial
time algorithms cannot solve
problems in regimes where blocks whose
order is the same as the underlying
problem instance require simultaneous
resolution.

Other parts of the paper show that certain NP problems can not be broken up in this manner. Thus NP/= P

Much of the paper is spent defining conditional independence and proving these two points.

一城柳絮吹成雪 2024-09-20 14:08:01

Dick Lipton 有一篇关于这篇论文及其第一印象的精彩博客文章。不幸的是,这也是技术性的。据我了解,Deolalikar的主要创新似乎是使用统计物理学和有限模型理论中的一些概念并将它们与问题联系起来。

我同意 Rex M 的观点,有些结果(主要是数学结果)无法向缺乏技术掌握的人表达。

Dick Lipton has a nice blog entry about the paper and his first impressions of it. Unfortunately, it also is technical. From what I can understand, Deolalikar's main innovation seems to be to use some concepts from statistical physics and finite model theory and tie them to the problem.

I'm with Rex M with this one, some results, mostly mathematical ones cannot be expressed to people who lack the technical mastery.

ペ泪落弦音 2024-09-20 14:08:01

我喜欢这个( http://www.newscientist.com/article/dn19287-p--np-its-bad-news-for-the-power-of-computing.html):

他的论点围绕着一个特定的任务,即布尔可满足性问题,该问题询问逻辑陈述的集合是否可以同时为真,或者它们是否相互矛盾。已知这是一个 NP 问题。

Deolalikar 声称已经证明
没有程序可以完成
它很快从头开始,并且它
因此不是P问题。他的
论证涉及巧妙地使用
统计物理学,因为他使用
数学结构如下
许多与随机相同的规则
物理系统。

上述效果可能相当显着:

如果结果成立,那就证明
P 和 NP 这两个类不是
相同,并施加严格的限制
计算机可以完成什么 –
这意味着许多任务可能是
从根本上来说,是不可简化的复杂性。

对于一些问题 – 包括
因式分解——结果不
明确说是否可以解决
迅速地。但有一个巨大的子类
称为“NP完全”的问题是
注定的。一个著名的例子是
旅行商问题——寻找
一组之间的最短路径
城市。此类问题可以检查
很快,但如果 P ≠ NP 则有
没有计算机程序可以完成
他们很快就从头开始。

I liked this ( http://www.newscientist.com/article/dn19287-p--np-its-bad-news-for-the-power-of-computing.html ):

His argument revolves around a particular task, the Boolean satisfiability problem, which asks whether a collection of logical statements can all be simultaneously true or whether they contradict each other. This is known to be an NP problem.

Deolalikar claims to have shown that
there is no program which can complete
it quickly from scratch, and that it
is therefore not a P problem. His
argument involves the ingenious use of
statistical physics, as he uses a
mathematical structure that follows
many of the same rules as a random
physical system.

The effects of the above can be quite significant:

If the result stands, it would prove
that the two classes P and NP are not
identical, and impose severe limits on
what computers can accomplish –
implying that many tasks may be
fundamentally, irreducibly complex.

For some problems – including
factorisation – the result does not
clearly say whether they can be solved
quickly. But a huge sub-class of
problems called "NP-complete" would be
doomed. A famous example is the
travelling salesman problem – finding
the shortest route between a set of
cities. Such problems can be checked
quickly, but if P ≠ NP then there is
no computer program that can complete
them quickly from scratch.

所有深爱都是秘密 2024-09-20 14:08:01

这是我对证明技术的理解:他使用一阶逻辑来表征所有多项式时间算法,然后表明对于具有某些属性的大型 SAT 问题,没有多项式时间算法可以确定其可满足性。

This is my understanding of the proof technique: he uses first order logic to characterize all polynomial time algorithms, and then shows that for large SAT problems with certain properties that no polynomial time algorithm can determine their satisfiability.

滿滿的愛 2024-09-20 14:08:01

另一种思考它的方式可能是完全错误的,但这是我在第一遍阅读时的第一印象是,我们认为在电路满意度中分配/清除项作为形成和破坏“有序”簇的过程。结构”,然后他使用统计物理学来表明多项式运算没有足够的速度来在特定的运算“相空间”中执行这些运算,因为这些“簇”最终相距太远。

One other way of thinking about it, which may be entirely wrong, but is my first impression as I'm reading it on the first pass, is that we think of assigning/clearing terms in circuit satisfaction as forming and breaking clusters of 'ordered structure', and that he's then using statistical physics to show that there isn't enough speed in the polynomial operations to perform those operations in a particular "phase space" of operations, because these "clusters" end up being too far apart.

折戟 2024-09-20 14:08:01

这样的证明必须涵盖所有类别的算法,例如连续全局优化

例如,在3-SAT问题中,我们必须评估变量以满足这些变量的三元组或其否定的所有替代方案。看看x OR y可以变成优化

((x-1)^2+y^2)((x-1)^2+(y-1)^2)(x^2+(y-1)^2)

和类似的三个变量的替代的七个术语。

找到所有项的此类多项式之和的全局最小值将解决我们的问题。 (来源

它超出了标准使用梯度方法、局部极小值去除方法、进化算法对连续世界进行组合技术。这是完全不同的王国 - 数值分析 - 我不相信这样的证明可以真正涵盖(?)

Such proof would have to cover all classes of algorithms, like continuous global optimization.

For example, in the 3-SAT problem we have to evaluate variables to fulfill all alternatives of triples of these variables or their negations. Look that x OR y can be changed into optimizing

((x-1)^2+y^2)((x-1)^2+(y-1)^2)(x^2+(y-1)^2)

and analogously seven terms for alternative of three variables.

Finding the global minimum of a sum of such polynomials for all terms would solve our problem. (source)

It's going out of standard combinatorial techniques to the continuous world using_gradient methods, local minims removing methods, evolutionary algorithms. It's completely different kingdom - numerical analysis - I don't believe such proof could really cover (?)

几度春秋 2024-09-20 14:08:01

值得注意的是,有了证据,“细节决定成败”。高层概述显然是这样的:

某种关系
之间的项目,表明这
关系意味着 X 并且
意味着 Y,因此我的论点是
显示。

我的意思是,它可能是通过 归纳 或任何其他形式的证明事情,但我'我想说的是,高层次的概述是没有用的。没有必要解释它。尽管这个问题本身与计算机科学有关,但最好还是留给数学家(认为这确实非常有趣)。

It's worth noting that with proofs, "the devil is in the detail". The high level overview is obviously something like:

Some some sort of relationship
between items, show that this
relationship implies X and that
implies Y and thus my argument is
shown.

I mean, it may be via Induction or any other form of proving things, but what I'm saying is the high level overview is useless. There is no point explaining it. Although the question itself relates to computer science, it is best left to mathematicians (thought it is certainly incredibly interesting).

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