We prove that matrix Fredholm determinants related to multi-time processes
can be expressed in terms of determinants of integrable kernels \`a la
Its-Izergin-Korepin-Slavnov (IIKS) and hence related to suitable
Riemann-Hilbert problems, thus extending the known results for the single-time
case. We focus on the Airy and Pearcey processes. As an example of applications
we re-deduce a third order PDE, found by Adler and van Moerbeke, for the
two-time Airy process.Comment: 18 pages, 1 figur