module Arith_rat:sig..end
Following Uwe Waldmann's work.
    Superposition, chaining and modulo reasoning for linear expressions, with
    congruence classes of terms and literals. Inferences are typically done with
    "scaled" literals, i.e. literals that are multiplied by numeric coefficients so
    as to bring the unified terms to the same coefficient.
module type S =sig..end
module Make:
val extension : Extensions.t