On discrete analytic functions: Products, Rational Functions, and some   Associated Reproducing Kernel Hilbert Spaces
  We introduce a family of discrete analytic functions, called expandable discrete analytic functions, which includes discrete analytic polynomials, and define two products in this family. The first one is defined in a way similar to the Cauchy-Kovalevskaya product of hyperholomorphic functions, and allows us to define rational discrete analytic functions. To define the second product we need a new space of entire functions which is contractively included in the Fock space. We study in this space some counterparts of Schur analysis. 
Daniel Alpay and Palle Jorgensen and Ron Seager and Dan Volok
math.FA math.CV