AF0005

factor_permutation_below_zero_impossible

Alpha v34 independently verified · alpha_closed; checked-use authorized; not Stable

There is no natural index below zero; empty list and permutation contracts are genuinely vacuous.

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 first-order arithmetic statement

forall i. (exists pfp_gap_empty. pfp_gap_empty + S (i) = (0)) -> false

Constructive proof overview

Generated structural guide

There is no natural index below zero; empty list and permutation contracts are genuinely vacuous.

The unchanged tactic script uses 1 declared prerequisite and contains 6 exact native proof lines.

Alpha v34 checked-use · first admitted v28 · independently kernel and Lean verified; not Stable

Proof neighborhood

Direct dependencies

le_zero Stable theorem; checked-use authorized

Direct dependents

Formal native tactic body

Dependencies are introduced as named hypotheses before line 1. Local theorem links identify exact declared prerequisites. This exact body belongs to a complete independently kernel-checked constructive proof bundle and has Alpha checked-use authority; it does not imply Stable membership.

Read the argument

Proof checkpoints

6 script commands · 2 reading checkpoints · 0 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.

01Fix variables and assumptionsL1–2

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

  1. L1
    intro i
  2. L2
    intro hi
02Use earlier factsL3–6

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

  1. L3
    apply PA1
  2. L4
    specialize le_zero (S i)
  3. L5
    apply le_zero
  4. L6
    exact hi

Library-wide reading audit

Original exact command ledger · 6 lines
  1. 0001intro i
  2. 0002intro hi
  3. 0003apply PA1
  4. 0004specialize le_zero (S i)
  5. 0005apply le_zero
  6. 0006exact hi