module Sigs:sig..end
module type SEQUENT =sig..end
module type DEFS =sig..end
module type NODE =sig..end
module type PROOF =sig..end
module type SEQTACTICS =sig..end
module type PROOFRULE =sig..end
module type ABDRULE =sig..end
module type PROVER =sig..end
module type ABDUCER =sig..end