PA006H · theorem

even_add_even

Stable checked-use theorem · independently closed

The sum of two even naturals is even.

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

∀ m. ∀ n. Even(m)Even(n)Even(m + n)

Every purple notation token opens its conservative definition. This is a reading surface; the compiler expands the statement before the unchanged kernel checks it.

Definitions used by this theorem

In the theorem statement

3 occurrences

In local proof propositions

none

0 occurrences

Exact expanded native-PA statement
forall m n. (exists a. m = 2 * a) -> (exists b. n = 2 * b) -> exists c. m + n = 2 * c

Proof neighborhood

Direct theorem prerequisites

Direct theorem dependents

Definition-aware tactic body

Only local propositions introduced by have or suffices are compacted. The untrusted compiler re-expands each one before the original tactic script is replayed; defined notation is never accepted by the kernel. Open the exact replay line beneath every changed command.

Read the argument

Proof checkpoints

10 script commands · 4 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 m
  2. L2
    intro n
  3. L3
    intro hm
  4. L4
    intro hn
02Separate the logical casesL5–6

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

  1. L5
    cases hm
  2. L6
    cases hn
03Construct an explicit witnessL7–7

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

  1. L7
    exists x + x1
04Calculate and transport equalitiesL8–10

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

  1. L8
    rewrite hm_witness
  2. L9
    rewrite hn_witness
  3. L10
    simp [mul_add]

Library-wide reading audit

Original defined command ledger · 10 lines
  1. 0001intro m
  2. 0002intro n
  3. 0003intro hm
  4. 0004intro hn
  5. 0005cases hm
  6. 0006cases hn
  7. 0007exists x + x1
  8. 0008rewrite hm_witness
  9. 0009rewrite hn_witness
  10. 0010simp [mul_add]