BT002E

divisor_one

Stable checked-use theorem · independently kernel verified

Every natural divisor of one equals one.

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 d. (exists y. 1 = d * y) -> d = 1

Structural proof guide

Every natural divisor of one equals one.

Direct prerequisites: mul_eq_one_components. The authored body proceeds by case analysis (2), intermediate claims (1).

Proof neighborhood

Direct dependencies

BT0020 mul_eq_one_components

Direct dependents

BT002X coprime_one_right BT002Y coprime_one_left BT0031 is_gcd_one_to_coprime BT004I beta_modulus_coprime_base BT00VB factorial_prime_le_of_divides

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

11 script commands · 6 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)
mul eq one components
01Fix variables and assumptionsL1–2

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

  1. L1
    intro d
  2. L2
    intro h
02Separate the logical casesL3–3

Follow the explicit conjunction, disjunction, witness, or contradiction step recorded below.

  1. L3
    cases h
03Use earlier factsL4–5

Instantiate or apply named facts and discharge the corresponding proof obligations.

  1. L4
    specialize mul_eq_one_components d
  2. L5
    specialize mul_eq_one_components x
04Establish partsL6–9

Establish this local claim before using it. It is not an additional assumption. The following proof commands apply mul eq one components.

  1. L6
    have parts : d = 1 /\ x = 1
  2. L7
    apply mul_eq_one_components
  3. L8
    symm
  4. L9
    exact h_witness
05Separate the logical casesL10–10

Follow the explicit conjunction, disjunction, witness, or contradiction step recorded below.

  1. L10
    cases parts
06Use earlier factsL11–11

Instantiate or apply named facts and discharge the corresponding proof obligations.

  1. L11
    exact parts_left

Library-wide reading audit

Original exact command ledger · 11 lines
  1. 0001intro d
  2. 0002intro h
  3. 0003cases h
  4. 0004specialize mul_eq_one_components d
  5. 0005specialize mul_eq_one_components x
  6. 0006have parts : d = 1 /\ x = 1
  7. 0007apply mul_eq_one_components
  8. 0008symm
  9. 0009exact h_witness
  10. 0010cases parts
  11. 0011exact parts_left