## The Annals of Probability

### Relative entropy and variational properties of generalized Gibbsian measures

#### Abstract

We study the relative entropy density for generalized Gibbs measures. We first show its existence and obtain a familiar expression in terms of entropy and relative energy for a class of “almost Gibbsian measures” (almost sure continuity of conditional probabilities). For quasilocal measures, we obtain a full variational principle. For the joint measures of the random field Ising model, we show that the weak Gibbs property holds, with an almost surely rapidly decaying translation-invariant potential. For these measures we show that the variational principle fails as soon as the measures lose the almost Gibbs property. These examples suggest that the class of weakly Gibbsian measures is too broad from the perspective of a reasonable thermodynamic formalism.

#### Article information

Source
Ann. Probab., Volume 32, Number 2 (2004), 1691-1726.

Dates
First available in Project Euclid: 18 May 2004

https://projecteuclid.org/euclid.aop/1084884868

Digital Object Identifier
doi:10.1214/009117904000000342

Mathematical Reviews number (MathSciNet)
MR2060315

Zentralblatt MATH identifier
1052.60042

#### Citation

Külske, Christof; Le Ny, Arnaud; Redig, Frank. Relative entropy and variational properties of generalized Gibbsian measures. Ann. Probab. 32 (2004), no. 2, 1691--1726. doi:10.1214/009117904000000342. https://projecteuclid.org/euclid.aop/1084884868

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