SL0001 · theorem body

prime_predecessor_nonzero

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

The predecessor of a prime cannot be zero.

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.

Statement with defined notation

∀ p. ∀ n. p = S n → Prime(p) → ¬n = 0

Every purple notation token opens its conservative definition. This reading surface never changes the unchanged intuitionistic kernel or confers checked-use authority.

Definitions used by this theorem

In the theorem statement

In local proof propositions

none
Exact expanded first-order statement
forall p n. p = S n -> ((~(p = 1) /\ forall frm_prime_left_qsm_prime frm_prime_right_qsm_prime. p = frm_prime_left_qsm_prime * frm_prime_right_qsm_prime -> frm_prime_left_qsm_prime = 1 \/ frm_prime_right_qsm_prime = 1)) -> ~(n = 0)

Proof neighborhood

Direct theorem prerequisites

none

Direct theorem dependents

Definition-aware tactic body

Only propositions whose conservative expansion has been checked for exact first-order equivalence are compacted. Every changed line retains its immutable exact replay command.

Read the argument

Proof checkpoints

10 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 assumptionsL1–4

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

  1. L1
    intro p
  2. L2
    intro n
  3. L3
    intro hpredecessor
  4. L4
    intro hprime
02Separate the logical casesL5–5

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

  1. L5
    cases hprime
03Fix variables and assumptionsL6–6

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

  1. L6
    intro hzero
04Use earlier factsL7–7

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

  1. L7
    apply hprime_left
05Calculate and transport equalitiesL8–10

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

  1. L8
    rewrite hpredecessor
  2. L9
    rewrite hzero
  3. L10
    refl

Library-wide reading audit

Original defined command ledger · 10 lines
  1. 0001intro p
  2. 0002intro n
  3. 0003intro hpredecessor
  4. 0004intro hprime
  5. 0005cases hprime
  6. 0006intro hzero
  7. 0007apply hprime_left
  8. 0008rewrite hpredecessor
  9. 0009rewrite hzero
  10. 0010refl