BT00U5 · Bertrand theorem

primorial_factor_choice_exists

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

Every index has its exact prime-or-one selector factor.

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

∀ i. ∃ a. Prime(S i) ∧ a = S i ∨ ¬Prime(S i) ∧ a = 1

Every purple notation token opens its conservative definition. Expanding the displayed statement recovers the exact first-order Peano-arithmetic formula checked by the unchanged kernel.

Definitions used by this theorem

In the theorem statement

2 occurrences

In local proof propositions

none

0 occurrences

Exact expanded native-PA statement
forall i. exists a. (((((~(S (i) = 1) /\ forall bpr_left_bpfc_exists_prime bpr_right_bpfc_exists_prime. S (i) = bpr_left_bpfc_exists_prime * bpr_right_bpfc_exists_prime -> bpr_left_bpfc_exists_prime = 1 \/ bpr_right_bpfc_exists_prime = 1)) /\ a = S (i)) \/ (~((~(S (i) = 1) /\ forall bpr_left_bpfc_exists_prime bpr_right_bpfc_exists_prime. S (i) = bpr_left_bpfc_exists_prime * bpr_right_bpfc_exists_prime -> bpr_left_bpfc_exists_prime = 1 \/ bpr_right_bpfc_exists_prime = 1)) /\ a = 1)))

Proof neighborhood

Direct theorem prerequisites

Direct theorem dependents

Definition-aware tactic body

Only local propositions introduced by have or suffices are compacted. Every changed line has an exact-AST conservative-expansion receipt; the kernel still receives the immutable original tactic script.

Read the argument

Proof checkpoints

13 script commands · 11 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.

Named ingredients (1)
01Fix variables and assumptionsL1–1

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

  1. L1
    intro i
02Use earlier factsL2–2

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

  1. L2
    specialize prime_decidable (S i)
03Separate the logical casesL3–3

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

  1. L3
    cases prime_decidable
04Construct an explicit witnessL4–4

Supply the displayed value, then prove that it has the required property.

  1. L4
    exists S i
05Separate the logical casesL5–6

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

  1. L5
    left
  2. L6
    split
06Use earlier factsL7–7

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

  1. L7
    exact prime_decidable_left
07Calculate and transport equalitiesL8–8

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

  1. L8
    refl
08Construct an explicit witnessL9–9

Supply the displayed value, then prove that it has the required property.

  1. L9
    exists 1
09Separate the logical casesL10–11

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

  1. L10
    right
  2. L11
    split
10Use earlier factsL12–12

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

  1. L12
    exact prime_decidable_right
11Calculate and transport equalitiesL13–13

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

  1. L13
    refl

Library-wide reading audit

Original defined command ledger · 13 lines
  1. 0001intro i
  2. 0002specialize prime_decidable (S i)
  3. 0003cases prime_decidable
  4. 0004exists S i
  5. 0005left
  6. 0006split
  7. 0007exact prime_decidable_left
  8. 0008refl
  9. 0009exists 1
  10. 0010right
  11. 0011split
  12. 0012exact prime_decidable_right
  13. 0013refl