Pieter Willem "Piet" Kasteleyn (12 October 1924 – 16 January 1996) was a Dutch physicist famous for his contributions to the field of statistical mechanics.
After finishing high school in 1942, Kasteleyn briefly studied chemistry in Amsterdam.
[1] In 1963 Kasteleyn was nominated Full Professor at the Lorentz Institute of Theoretical Physics in Leiden.
While investigating dimers on a square lattice (essentially a domino tiling), he independently discovered combinatorial Fisher-Kasteleyn-Temperley algorithm.
[3] In a series of papers with C. M. Fortuin[4] he developed random cluster model and obtained the FKG inequality.