BT001J · Bertrand theorem

le_not_lt

Stable checked-use theorem · independently kernel verified

A weak inequality excludes strict inequality in the reverse direction.

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

∀ a. ∀ b. Le(a,b) → ¬Lt(b,a)

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 a b. (exists k. k + a = b) -> ~ (exists k. k + S b = a)

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

9 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.

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 assumptionsL1–4

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

  1. L1
    intro a
  2. L2
    intro b
  3. L3
    intro hab
  4. L4
    intro hba
02Use earlier factsL5–9

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

  1. L5
    specialize lt_not_le b
  2. L6
    specialize lt_not_le a
  3. L7
    apply lt_not_le
  4. L8
    exact hba
  5. L9
    exact hab

Library-wide reading audit

Original defined command ledger · 9 lines
  1. 0001intro a
  2. 0002intro b
  3. 0003intro hab
  4. 0004intro hba
  5. 0005specialize lt_not_le b
  6. 0006specialize lt_not_le a
  7. 0007apply lt_not_le
  8. 0008exact hba
  9. 0009exact hab