anchor.diff:  open canon
   open meson
   open quot
  -open pair
  +//open pair
   open nums
   open recursion
   
  
positive.code: (* Maximum and minimum of natural numbers.                                   *)
  (* ------------------------------------------------------------------------- *)
  let MAX = 
      new_definition(parse_term @"!m n. MAX m n = if m <= n |>THEN<| n else m")
  
  let MIN = 
      new_definition(parse_term @"!m n. MIN m n = if m <= n |>THEN<| m else n")
  
  (* ------------------------------------------------------------------------- *)
  (* Step cases.                                                               *)
  
negative.code: 
  let EXP_ZERO = 
      prove
          ((parse_term @"!n. 0 EXP n = if n = 0 then 1 else 0"), //((parse_term @"!n. 0 EXP n = if n = 0 |>THEN<| 1 else 0"), 
           GEN_TAC
           |> THEN <| COND_CASES_TAC
           |> THEN <| ASM_REWRITE_TAC [EXP_EQ_0; EXP_EQ_1])
  