Temperature Correlations of Quantum Spins
  Isotropic XY is considered. It describes interaction of quantum spins on 1-dimesional lattice. Alternatevly one can call the model XXO Hiesenberg antiferromagnet. We solved long standing problem of evaluation of temperature corelations. We proved that correlation function of the model is $\tau $ function of Ablowitz-Ladik PDE. We explicitly evaluated asymptotics. 
A.R.Its, A.G.Izergin, V.E.Korepin, N.A.Slavnov