PF000Z · theorem body

pythagorean_primitive_legs_not_both_even

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

The two legs of a primitive Pythagorean triple cannot both have even witnesses.

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

∀ x. ∀ y. ∀ z. PrimitivePythagorean(x,y,z)Even(x) → ¬Even(y)

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 x y z. ((((x) * (x) + (y) * (y) = (z) * (z)) /\ (forall pff_divisor_pairwise_source. (exists pff_left_pairwise_source. (x) = pff_divisor_pairwise_source * pff_left_pairwise_source) -> (exists pff_right_pairwise_source. (y) = pff_divisor_pairwise_source * pff_right_pairwise_source) -> pff_divisor_pairwise_source = 1))) -> (exists a. x = 2 * a) -> (exists b. y = 2 * b) -> false

Proof neighborhood

Direct theorem prerequisites

prime_two · 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

13 script commands · 3 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 assumptionsL1–6

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

  1. L1
    intro x
  2. L2
    intro y
  3. L3
    intro z
  4. L4
    intro hprimitive
  5. L5
    intro hx
  6. L6
    intro hy
02Separate the logical casesL7–8

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

  1. L7
    cases hprimitive
  2. L8
    cases prime_two
03Use earlier factsL9–13

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

  1. L9
    apply prime_two_left
  2. L10
    specialize hprimitive_right 2
  3. L11
    apply hprimitive_right
  4. L12
    exact hx
  5. L13
    exact hy

Library-wide reading audit

Original defined command ledger · 13 lines
  1. 0001intro x
  2. 0002intro y
  3. 0003intro z
  4. 0004intro hprimitive
  5. 0005intro hx
  6. 0006intro hy
  7. 0007cases hprimitive
  8. 0008cases prime_two
  9. 0009apply prime_two_left
  10. 0010specialize hprimitive_right 2
  11. 0011apply hprimitive_right
  12. 0012exact hx
  13. 0013exact hy