anchor.diff:  (* ------------------------------------------------------------------------- *)
   (* The unary operations; all easy.                                           *)
   (* ------------------------------------------------------------------------- *)
  +
   /// Conversion to negate a rational literal of type :real.
   let REAL_RAT_NEG_CONV = 
       let pth = 
  
positive.code:             let! d1' = mk_realintconst d1n
              let! d2' = mk_realintconst d2n
              let th0 = 
                  INST [x1', x1
                        y1', y1
                        x2', x2
                        y2', y2
                        u1', u1
                        v1', v1
                        u2', u2
                        v2', v2
                        d1', d1
                        d2', d2] pth_cancel
              let th1 = EQT_ELIM(REAL_INT_REDUCE_CONV(Choice.get <| lhand(concl <| Choice.get th0)))
              let th2 = MP th0 th1
  
negative.code: (* ------------------------------------------------------------------------- *)
  (* Relational operations.                                                    *)
  (* ------------------------------------------------------------------------- *)
  
  /// Conversion to prove whether one rational literal of type :real is <= another.
  let REAL_RAT_LE_CONV = 
      let pth = 
  