Random Words, Toeplitz Determinants and Integrable Systems. II
  This paper, a continuation of math.CO/9909169, connects the analysis of the length of the longest weakly increasing subsequence of inhomogeneous random words to a Riemann-Hilbert problem and an associated system of integrable PDEs. In particular, we show that the Poissonization of the distribution function of this length can be identified as the Jimbo-Miwa-Ueno tau function. 
Alexander R. Its, Craig A. Tracy and Harold Widom