anchor.diff:  /// Conversion to prove whether one rational literal of type :real is >= another.
   let REAL_RAT_GE_CONV = GEN_REWRITE_CONV I [real_ge]
                          |> THENC <| REAL_RAT_LE_CONV
  +
   /// Conversion to prove whether one rational literal of type :real is > another.
   let REAL_RAT_GT_CONV = GEN_REWRITE_CONV I [real_gt]
                          |> THENC <| REAL_RAT_LT_CONV
  
positive.code:   let y1 = (parse_term @"y1:real")
    let y2 = (parse_term @"y2:real")
    let y3 = (parse_term @"y3:real")
    let RAW_REAL_RAT_ADD_CONV tm = 
      choice {
           let r1, r2 = dest_addop tm
  
negative.code:                     |> THENC <| REAL_INT_MUL_CONV) tm3
           return! MP th1 (TRANS th2 (SYM th3))
      }
  
    BINOP_CONV REAL_INT_RAT_CONV
    |> THENC <| RAW_REAL_RAT_ADD_CONV
    |> THENC <| TRY_CONV(GEN_REWRITE_CONV I [REAL_DIV_1])
  