Hostname: page-component-6898cfcb55-zsp5v Total loading time: 0 Render date: 2026-11-12T01:00:22.374Z Has data issue: false hasContentIssue false

Zero-one laws with variable probability

Published online by Cambridge University Press:  12 March 2014

Joel Spencer*
Affiliation:
Departments of Mathematics and Computer Science, Courant Institute, New York, New York, 10012, E-mail: spencer@cs.nyu.edu

Extract

One of this author's favorite theorems has long been the Zero-One law discovered independently by Glebskii et al. [12] and Ron Fagin [10]. Let A be any first-order property of graphs and let µn(A) be the proportion of labelled graphs on n vertices for which A holds. Then

This result has inspired much work by logicians, generally in the direction of showing (1) for some powerful languages. Thus it is known [5] that (1) holds when A is a sentence in fixed point logic and it is known [13] that (1) does not always hold when A is a sentence in second-order monadic logic. Here, however, we explore recent work in a totally different direction. Let G(n, p) denote the random graph on n vertices with edge probability p. (In §2 we define the random structures we will deal with.) A property A is an event in the probability space and Pr[G(n, p) ╞ A] is well defined. When p = 1/2, each labelled graph on n vertices has equal weight so that (1) may be rewritten

Fagin's proof actually gives that (2) holds for any constant 0 < p < 1.

Information

Type
Survey/expository paper
Copyright
Copyright © Association for Symbolic Logic 1993

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Article purchase

Temporarily unavailable