TF0007

three_mod_four_progression_nonzero

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

Every witnessed natural of the form 4k+3 is nonzero.

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 n. (exists ff_residue_ptmf_number. (n) = 4 * ff_residue_ptmf_number + 3) -> ~(n = 0)

Constructive proof overview

Generated structural guide

Every witnessed natural of the form 4k+3 is nonzero.

The unchanged tactic script uses 0 declared prerequisites and contains 8 exact native proof lines.

Alpha v34 checked-use · first admitted v23 · independently kernel and Lean verified; not Stable

Proof neighborhood

Direct dependencies

none

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

8 script commands · 4 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 assumptionsL1–3

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

  1. L1
    intro n
  2. L2
    intro hthree
  3. L3
    intro hzero
02Separate the logical casesL4–4

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

  1. L4
    cases hthree
03Calculate and transport equalitiesL5–6

Carry out the recorded arithmetic or equality steps; inspect the exact commands for their direction and premises.

  1. L5
    rewrite hthree_witness at hzero
  2. L6
    rewrite PA4 at hzero
04Use earlier factsL7–8

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

  1. L7
    apply PA1
  2. L8
    exact hzero

Library-wide reading audit

Original exact command ledger · 8 lines
  1. 0001intro n
  2. 0002intro hthree
  3. 0003intro hzero
  4. 0004cases hthree
  5. 0005rewrite hthree_witness at hzero
  6. 0006rewrite PA4 at hzero
  7. 0007apply PA1
  8. 0008exact hzero