FS0032 · theorem body

four_square_lagrange_from_strict_descent

dependency-curried kernel-checked candidate body; not enrolled in Alpha or Stable

The all-natural Lagrange four-square theorem follows from exactly one remaining explicit hypothesis: uniform strict prime-multiple descent.

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. Prime(x) → ¬y = 0 → ¬y = 1 → (∃ z. ∃ n. ∃ m. ∃ k. x · y = z · z + n · n + m · m + k · k) → ∃ z. ¬z = 0 ∧ (Lt(z,y) ∧ (∃ n. ∃ m. ∃ k. ∃ i. x · z = n · n + m · m + k · k + i · i))) → ∀ x. ∃ y. ∃ z. ∃ n. ∃ m. x = y · y + z · z + n · n + m · m

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 fsd_prime_bridge fsd_multiplier_bridge. ((~(fsd_prime_bridge = 1) /\ forall frm_prime_left_fsd_bridge_prime frm_prime_right_fsd_bridge_prime. fsd_prime_bridge = frm_prime_left_fsd_bridge_prime * frm_prime_right_fsd_bridge_prime -> frm_prime_left_fsd_bridge_prime = 1 \/ frm_prime_right_fsd_bridge_prime = 1)) -> ~(fsd_multiplier_bridge = 0) -> ~(fsd_multiplier_bridge = 1) -> (exists fsl_a_fsd_bridge_source fsl_b_fsd_bridge_source fsl_c_fsd_bridge_source fsl_d_fsd_bridge_source. (fsd_prime_bridge * fsd_multiplier_bridge) = fsl_a_fsd_bridge_source * fsl_a_fsd_bridge_source + fsl_b_fsd_bridge_source * fsl_b_fsd_bridge_source + fsl_c_fsd_bridge_source * fsl_c_fsd_bridge_source + fsl_d_fsd_bridge_source * fsl_d_fsd_bridge_source) -> exists fsd_smaller_bridge. (~(fsd_smaller_bridge = 0) /\ ((exists fsd_gap_bridge. fsd_gap_bridge + S fsd_smaller_bridge = fsd_multiplier_bridge) /\ (exists fsl_a_fsd_bridge_target fsl_b_fsd_bridge_target fsl_c_fsd_bridge_target fsl_d_fsd_bridge_target. (fsd_prime_bridge * fsd_smaller_bridge) = fsl_a_fsd_bridge_target * fsl_a_fsd_bridge_target + fsl_b_fsd_bridge_target * fsl_b_fsd_bridge_target + fsl_c_fsd_bridge_target * fsl_c_fsd_bridge_target + fsl_d_fsd_bridge_target * fsl_d_fsd_bridge_target)))) -> forall n. (exists fsl_a_fslb_natural_result fsl_b_fslb_natural_result fsl_c_fslb_natural_result fsl_d_fslb_natural_result. (n) = fsl_a_fslb_natural_result * fsl_a_fslb_natural_result + fsl_b_fslb_natural_result * fsl_b_fslb_natural_result + fsl_c_fslb_natural_result * fsl_c_fslb_natural_result + fsl_d_fslb_natural_result * fsl_d_fslb_natural_result)

Proof neighborhood

Direct theorem prerequisites

Direct theorem dependents

none

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

4 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 (2)
01Fix variables and assumptionsL1–1

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

  1. L1
    intro hstep
02Use earlier factsL2–4

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

  1. L2
    apply four_square_lagrange_from_all_primes
  2. L3
    apply four_square_prime_from_strict_descent
  3. L4
    exact hstep

Library-wide reading audit

Original defined command ledger · 4 lines
  1. 0001intro hstep
  2. 0002apply four_square_lagrange_from_all_primes
  3. 0003apply four_square_prime_from_strict_descent
  4. 0004exact hstep