This note gives a general construction of an integrable lattice model (and a
solution of the Yang-Baxter equation with spectral parameter) from a
four-dimensional field theory which is a mixture of topological and
holomorphic. Spin-chain models arise in this way from a twisted, deformed
version of N=1 gauge theory.Comment: Based on the longer paper arXiv:1303.2632 and on my talk at
  String-Math 2013. 9 figure