BT00QW

pow_two_base_two_value_four

Alpha v34 checked-use theorem · independently kernel and Lean verified; not Stable

The relational square of two has the concrete value four.

Current library: Alpha v34, 4,223 checked-use theorems; Stable remains 432. Historical first admissions, original proof editions, and non-admitted aliases are preserved. Exact original first-admission records.

Exact expanded PA statement

forall x. (exists pa_b_bie_two_two pa_c_bie_two_two. ((forall pa_i_bie_two_two_repeat. (exists pa_lt_bie_two_two_repeat_bound. pa_lt_bie_two_two_repeat_bound + S pa_i_bie_two_two_repeat = 2) -> (((exists pa_h_bie_two_two_repeat_decoded. pa_h_bie_two_two_repeat_decoded + S (2) = S ((S (pa_i_bie_two_two_repeat)) * pa_c_bie_two_two)) /\ exists pa_q_bie_two_two_repeat_decoded. pa_b_bie_two_two = pa_q_bie_two_two_repeat_decoded * S ((S (pa_i_bie_two_two_repeat)) * pa_c_bie_two_two) + (2)))) /\ (exists pa_u_bie_two_two_product pa_v_bie_two_two_product. ((((exists pa_h_bie_two_two_product_start. pa_h_bie_two_two_product_start + S (1) = S ((S (0)) * pa_v_bie_two_two_product)) /\ exists pa_q_bie_two_two_product_start. pa_u_bie_two_two_product = pa_q_bie_two_two_product_start * S ((S (0)) * pa_v_bie_two_two_product) + (1))) /\ ((((exists pa_h_bie_two_two_product_terminal. pa_h_bie_two_two_product_terminal + S (x) = S ((S (2)) * pa_v_bie_two_two_product)) /\ exists pa_q_bie_two_two_product_terminal. pa_u_bie_two_two_product = pa_q_bie_two_two_product_terminal * S ((S (2)) * pa_v_bie_two_two_product) + (x))) /\ forall pa_i_bie_two_two_product. (exists pa_lt_bie_two_two_product_bound. pa_lt_bie_two_two_product_bound + S pa_i_bie_two_two_product = 2) -> exists pa_p_bie_two_two_product pa_r_bie_two_two_product pa_s_bie_two_two_product. ((((exists pa_h_bie_two_two_product_factor. pa_h_bie_two_two_product_factor + S (pa_p_bie_two_two_product) = S ((S (pa_i_bie_two_two_product)) * pa_c_bie_two_two)) /\ exists pa_q_bie_two_two_product_factor. pa_b_bie_two_two = pa_q_bie_two_two_product_factor * S ((S (pa_i_bie_two_two_product)) * pa_c_bie_two_two) + (pa_p_bie_two_two_product))) /\ ((((exists pa_h_bie_two_two_product_partial. pa_h_bie_two_two_product_partial + S (pa_r_bie_two_two_product) = S ((S (pa_i_bie_two_two_product)) * pa_v_bie_two_two_product)) /\ exists pa_q_bie_two_two_product_partial. pa_u_bie_two_two_product = pa_q_bie_two_two_product_partial * S ((S (pa_i_bie_two_two_product)) * pa_v_bie_two_two_product) + (pa_r_bie_two_two_product))) /\ ((((exists pa_h_bie_two_two_product_successor. pa_h_bie_two_two_product_successor + S (pa_s_bie_two_two_product) = S ((S (S pa_i_bie_two_two_product)) * pa_v_bie_two_two_product)) /\ exists pa_q_bie_two_two_product_successor. pa_u_bie_two_two_product = pa_q_bie_two_two_product_successor * S ((S (S pa_i_bie_two_two_product)) * pa_v_bie_two_two_product) + (pa_s_bie_two_two_product))) /\ pa_s_bie_two_two_product = pa_r_bie_two_two_product * pa_p_bie_two_two_product)))))))) -> x = 4

Structural proof guide

The relational square of two has the concrete value four.

Direct prerequisites: pow_two. The authored body proceeds by intermediate claims (1), closed numeral normalization (1).

Proof neighborhood

Direct dependencies

Direct dependents

Formal native tactic body

Dependencies are hypotheses of the historical Alpha-v12 body receipt. The complete historical Alpha-v18 proof bundle independently checks every dependency; current Alpha v25 preserves that checked theorem use without changing Stable membership.

Read the argument

Proof checkpoints

12 script commands · 2 reading checkpoints · 1 local claims

This is a reading aid, not a new proof or a proof-tree certificate. Checkpoint groups are consecutive commands, not inferred branch boundaries. Every step links to the preserved script.

Named ingredients (1)
01Fix variables and assumptionsL1–2

Work with arbitrary variables or the premises of the current implication.

  1. L1
    intro x
  2. L2
    intro hx
02Establish hxxL3–12

Establish this local claim before using it. It is not an additional assumption. The following proof commands apply pow two.

  1. L3
    have hxx : x = 2 * 2
  2. L4
    specialize pow_two 2
  3. L5
    specialize pow_two 2
  4. L6
    specialize pow_two x
  5. L7
    apply pow_two
  6. L8
    refl
  7. L9
    exact hx
  8. L10
    trans 2 * 2
  9. L11
    exact hxx
  10. L12
    norm_num

Library-wide reading audit

Original exact command ledger · 12 lines
  1. 0001intro x
  2. 0002intro hx
  3. 0003have hxx : x = 2 * 2
  4. 0004specialize pow_two 2
  5. 0005specialize pow_two 2
  6. 0006specialize pow_two x
  7. 0007apply pow_two
  8. 0008refl
  9. 0009exact hx
  10. 0010trans 2 * 2
  11. 0011exact hxx
  12. 0012norm_num