Sch\"utzenberger Products in a Category
  The Sch\"utzenberger product of monoids is a key tool for the algebraic treatment of language concatenation. In this paper we generalize the Sch\"utzenberger product to the level of monoids in an algebraic category $\mathscr{D}$, leading to a uniform view of the corresponding constructions for monoids (Sch\"utzenberger), ordered monoids (Pin), idempotent semirings (Kl\'ima and Pol\'ak) and algebras over a field (Reutenauer). In addition, assuming that $\mathscr{D}$ is part of a Stone-type duality, we derive a characterization of the languages recognized by Sch\"utzenberger products. 
Liang-Ting Chen, Henning Urbat
cs.FL