arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0902.1327math.COmath.PR
收藏

随机图与图的弱正星形

Random Graphons and a Weak Positivstellensatz for Graphs

László Lovász, Balázs Szegedy

摘要:

在早期的论文中,作者证明了收敛图序列的极限可以用各种结构来描述,包括某些称为图子的2-变量实函数,满足某些一致性条件的随机图模型,以及归一化,乘法和反射正图参数。在本文中,我们表明,这些结构中的每一个都有一个相关的,放松的版本,这也是等价的。利用这一点,我们描述了一个进一步的结构相当于图的限制,即概率测度可数图遍历相对于组的置换的节点。作为一个应用程序,我们证明了一个类似的Positivstellenquiry的图:我们表明,每一个线性不等式之间的子图的密度,持有渐近的所有图有一个正式的证明在以下意义上:它可以近似任意以及由另一个有效的不等式,是一个“平方和”的代数部分标号图。

英文摘要:

In an earlier paper the authors proved that limits of convergent graph sequences can be described by various structures, including certain 2-variable real functions called graphons, random graph models satisfying certain consistency conditions, and normalized, multiplicative and reflection positive graph parameters. In this paper we show that each of these structures has a related, relaxed version, which are also equivalent. Using this, we describe a further structure equivalent to graph limits, namely probability measures on countable graphs that are ergodic with respect to the group of permutations of the nodes. As an application, we prove an analogue of the Positivstellensatz for graphs: We show that every linear inequality between subgraph densities that holds asymptotically for all graphs has a formal proof in the following sense: it can be approximated arbitrarily well by another valid inequality that is a "sum of squares" in the algebra of partially labeled graphs.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑