module External:sig..end
This module defines a safe interface for the core solver.
It is the basis of the Solver and Mcsolver modules.
module type S = Solver_intf.Smodule Make:functor (St:Solver_types.S) ->functor (Th:Plugin_intf.Swith type term = St.term and type formula = St.formula and type proof = St.proof) ->