PF002D · theorem body

fermat_four_double_product_commute

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

The factor two may pass a natural factor using explicit associativity and commutativity.

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

forall m n. m * (2 * n) = 2 * (m * n)

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

none

In local proof propositions

none
Exact expanded first-order statement
forall m n. m * (2 * n) = 2 * (m * n)

Proof neighborhood

Direct theorem prerequisites

mul_assoc · Stable closed mul_comm · Stable closed

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 · 7 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 assumptionsL1–2

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

  1. L1
    intro m
  2. L2
    intro n
02Calculate and transport equalitiesL3–4

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

  1. L3
    trans (m * 2) * n
  2. L4
    symm
03Use earlier factsL5–5

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

  1. L5
    apply mul_assoc
04Calculate and transport equalitiesL6–7

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

  1. L6
    trans (2 * m) * n
  2. L7
    congr
05Use earlier factsL8–8

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

  1. L8
    apply mul_comm
06Calculate and transport equalitiesL9–9

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

  1. L9
    refl
07Use earlier factsL10–10

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

  1. L10
    apply mul_assoc

Library-wide reading audit

Original defined command ledger · 10 lines
  1. 0001intro m
  2. 0002intro n
  3. 0003trans (m * 2) * n
  4. 0004symm
  5. 0005apply mul_assoc
  6. 0006trans (2 * m) * n
  7. 0007congr
  8. 0008apply mul_comm
  9. 0009refl
  10. 0010apply mul_assoc