PA005D

predecessor_square_mod_one

Stable checked-use theorem · independently closed

The predecessor of a successor squares to one modulo that successor.

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.

Exact expanded PA statement

forall p r. p = S r -> exists gs_u_square gs_v_square. (r * r) + p * gs_u_square = (1) + p * gs_v_square

Structural proof guide

Generated structural guide

The predecessor of a successor squares to one modulo that successor.

Use the direct prerequisites mul_one, mul_succ_left, add_assoc, add_comm, zero_add, add_succ_left as previously established PA formulas.

The proof proceeds by equality transport (2), certified simplification (1).

Referenced ingredients

Proof neighborhood

Direct dependencies

Direct dependents

Formal native tactic body

Dependencies are introduced as named hypotheses before line 1. Linked names are exact direct references. This Stable checked-use theorem is independently kernel-checked when replayed.

Read the argument

Proof checkpoints

8 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.

01Fix variables and assumptionsL1–3

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

  1. L1
    intro p
  2. L2
    intro r
  3. L3
    intro hp
02Construct an explicit witnessL4–5

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

  1. L4
    exists 1
  2. L5
    exists r
03Calculate and transport equalitiesL6–8

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

  1. L6
    rewrite hp
  2. L7
    rewrite hp
  3. L8
    simp [mul_one, mul_succ_left, add_assoc, add_comm, zero_add, add_succ_left]

Library-wide reading audit

Original exact command ledger · 8 lines
  1. 0001intro p
  2. 0002intro r
  3. 0003intro hp
  4. 0004exists 1
  5. 0005exists r
  6. 0006rewrite hp
  7. 0007rewrite hp
  8. 0008simp [mul_one, mul_succ_left, add_assoc, add_comm, zero_add, add_succ_left]