BT0042

beta_at_unique

Stable · empty-context checked

The decoded residue at a Gödel-beta position is unique.

Exact expanded PA statement

forall b c i x y. ((exists h. h + S x = S ((S i) * c)) /\ exists q. b = q * S ((S i) * c) + x) -> ((exists h. h + S y = S ((S i) * c)) /\ exists q. b = q * S ((S i) * c) + y) -> x = y

Structural proof guide

The decoded residue at a Gödel-beta position is unique.

Direct prerequisites: mul_comm, division_remainder_unique. The authored body proceeds by case analysis (5), intermediate claims (3).

Proof neighborhood

Direct dependencies

Direct dependents

Formal native tactic body

Dependencies are hypotheses of this body receipt. The focused endpoint audits separately check the complete empty-context certificates.

  1. 0001intro b
  2. 0002intro c
  3. 0003intro i
  4. 0004intro x
  5. 0005intro y
  6. 0006intro hx
  7. 0007intro hy
  8. 0008cases hx
  9. 0009cases hy
  10. 0010cases hx_right
  11. 0011cases hy_right
  12. 0012have hdx : b = S ((S i) * c) * x1 + x
  13. 0013trans x1 * S ((S i) * c) + x
  14. 0014exact hx_right_witness
  15. 0015congr
  16. 0016apply mul_comm
  17. 0017refl
  18. 0018have hdy : b = S ((S i) * c) * x2 + y
  19. 0019trans x2 * S ((S i) * c) + y
  20. 0020exact hy_right_witness
  21. 0021congr
  22. 0022apply mul_comm
  23. 0023refl
  24. 0024specialize division_remainder_unique (S ((S i) * c))
  25. 0025specialize division_remainder_unique b
  26. 0026specialize division_remainder_unique x1
  27. 0027specialize division_remainder_unique x
  28. 0028specialize division_remainder_unique x2
  29. 0029specialize division_remainder_unique y
  30. 0030have huniq : x1 = x2 /\ x = y
  31. 0031apply division_remainder_unique
  32. 0032exact hdx
  33. 0033exact hx_left
  34. 0034exact hdy
  35. 0035exact hy_left
  36. 0036cases huniq
  37. 0037exact huniq_right