BT008Y

factorial_exists

Stable ยท empty-context checked

Every natural has a beta-coded relational factorial value.

Exact expanded PA statement

forall n. exists z. (exists ff_b_exists ff_c_exists. ((forall ff_i_exists_range. (exists ff_lt_exists_range_bound. ff_lt_exists_range_bound + S ff_i_exists_range = n) -> (((exists ff_h_exists_range_decoded. ff_h_exists_range_decoded + S (1 + ff_i_exists_range) = S ((S (ff_i_exists_range)) * ff_c_exists)) /\ exists ff_q_exists_range_decoded. ff_b_exists = ff_q_exists_range_decoded * S ((S (ff_i_exists_range)) * ff_c_exists) + (1 + ff_i_exists_range)))) /\ (exists ff_u_exists_product ff_v_exists_product. ((((exists ff_h_exists_product_start. ff_h_exists_product_start + S (1) = S ((S (0)) * ff_v_exists_product)) /\ exists ff_q_exists_product_start. ff_u_exists_product = ff_q_exists_product_start * S ((S (0)) * ff_v_exists_product) + (1))) /\ ((((exists ff_h_exists_product_terminal. ff_h_exists_product_terminal + S (z) = S ((S (n)) * ff_v_exists_product)) /\ exists ff_q_exists_product_terminal. ff_u_exists_product = ff_q_exists_product_terminal * S ((S (n)) * ff_v_exists_product) + (z))) /\ forall ff_i_exists_product. (exists ff_lt_exists_product_bound. ff_lt_exists_product_bound + S ff_i_exists_product = n) -> exists ff_p_exists_product ff_r_exists_product ff_s_exists_product. ((((exists ff_h_exists_product_factor. ff_h_exists_product_factor + S (ff_p_exists_product) = S ((S (ff_i_exists_product)) * ff_c_exists)) /\ exists ff_q_exists_product_factor. ff_b_exists = ff_q_exists_product_factor * S ((S (ff_i_exists_product)) * ff_c_exists) + (ff_p_exists_product))) /\ ((((exists ff_h_exists_product_partial. ff_h_exists_product_partial + S (ff_r_exists_product) = S ((S (ff_i_exists_product)) * ff_v_exists_product)) /\ exists ff_q_exists_product_partial. ff_u_exists_product = ff_q_exists_product_partial * S ((S (ff_i_exists_product)) * ff_v_exists_product) + (ff_r_exists_product))) /\ ((((exists ff_h_exists_product_successor. ff_h_exists_product_successor + S (ff_s_exists_product) = S ((S (S ff_i_exists_product)) * ff_v_exists_product)) /\ exists ff_q_exists_product_successor. ff_u_exists_product = ff_q_exists_product_successor * S ((S (S ff_i_exists_product)) * ff_v_exists_product) + (ff_s_exists_product))) /\ ff_s_exists_product = ff_r_exists_product * ff_p_exists_product))))))))

Structural proof guide

Every natural has a beta-coded relational factorial value.

Direct prerequisites: beta_range_exists, beta_product_exists. The authored body proceeds by case analysis (5), intermediate claims (1).

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 n
  2. 0002have hrange : exists b c. (forall i. (exists h. h + S i = n) -> ((exists h. h + S (1 + i) = S ((S i) * c)) /\ exists q. b = q * S ((S i) * c) + (1 + i)))
  3. 0003specialize beta_range_exists 1
  4. 0004specialize beta_range_exists n
  5. 0005exact beta_range_exists
  6. 0006cases hrange
  7. 0007cases hrange_witness
  8. 0008specialize beta_product_exists x
  9. 0009specialize beta_product_exists x1
  10. 0010specialize beta_product_exists n
  11. 0011cases beta_product_exists
  12. 0012cases beta_product_exists_witness
  13. 0013cases beta_product_exists_witness_witness
  14. 0014exists x2
  15. 0015exists x
  16. 0016exists x1
  17. 0017split
  18. 0018exact hrange_witness_witness
  19. 0019exists x3
  20. 0020exists x4
  21. 0021exact beta_product_exists_witness_witness_witness