Graph-Based Logic and Sketches II: Finite-Product Categories and   Equational Logic (Preliminary Report)
  It is shown that the proof theory for sketches and forms provided in Part I of this paper (see http://www.cwru.edu/1/class/mans/math/pub/wells) is strong enough to produce all the theorems of the entailment system for multisorted equational logic provided in Goguen and Meseguer's article ``Completeness of many-sorted equational logic'' (Technical Report CSL-135, SRI International Computer Science Laboratory, 333 Ravenswood Ave., Menlo Park, CA 94025, USA, 1982). 
Atish Bagchi, Charles Wells