SK0008

nonzero_square_factor_root

The square-root factor of a positive input is itself nonzero.

Alpha v34 checked-use · first admitted v29 · independently kernel and Lean verified; not Stable

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.

For n>1 the exponent gcd and a real beta table classify and witness all positive root degrees. The unit n=1 has a separate uniform certificate for every positive degree. Zero is excluded. NaturalSquarefreeDecomposition is deliberately distinct from the unrelated polynomial definition.

Exact theorem in conservative defined notation

∀ n. ∀ r. ∀ s. ¬n = 0 → n = r · (s · s) → ¬s = 0

Every linked abbreviation expands hygienically to the identical original native formula.

Definition DAG

none

Actual proof prerequisites

none
Original expanded first-order statement
forall n r s. ~(n = 0) -> n = r * (s * s) -> ~(s = 0)

Complete tactic proof in conservative notation

All 12 original proof lines are preserved. Only local proposition formulas are abbreviated; every abbreviation has an exact binder-safe expansion check. The linked exact edition contains the unchanged replay script.

Read the argument

Proof checkpoints

12 script commands · 5 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.

Definition notation is shown below. Open the paired exact edition for the original native formulas. Source pairing is not a new equivalence certificate.

01Fix variables and assumptionsL1–6

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

  1. L1
    intro n
  2. L2
    intro r
  3. L3
    intro s
  4. L4
    intro hn
  5. L5
    intro heq
  6. L6
    intro hszero
02Use earlier factsL7–7

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

  1. L7
    apply hn
03Calculate and transport equalitiesL8–8

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

  1. L8
    trans r * (s * s)
04Use earlier factsL9–9

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

  1. L9
    exact heq
05Calculate and transport equalitiesL10–12

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

  1. L10
    rewrite hszero
  2. L11
    rewrite hszero
  3. L12
    simp

Library-wide reading audit

Original defined command ledger · 12 lines
  1. 0001intro n
  2. 0002intro r
  3. 0003intro s
  4. 0004intro hn
  5. 0005intro heq
  6. 0006intro hszero
  7. 0007apply hn
  8. 0008trans r * (s * s)
  9. 0009exact heq
  10. 0010rewrite hszero
  11. 0011rewrite hszero
  12. 0012simp