BA0004

cf_approximation_prepend_error_backward

Alpha v34 independently verified · alpha_closed; checked-use authorized; not Stable

The opposite signed numerator error transports with the same nonnegative magnitude.

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 first-order arithmetic statement

forall a b q r x y e. a = b * q + r -> r * x = b * y + e -> a * x = b * (q * x + y) + e

Constructive proof overview

Generated structural guide

The opposite signed numerator error transports with the same nonnegative magnitude.

The unchanged tactic script uses 6 declared prerequisites and contains 14 exact native proof lines.

Alpha v34 checked-use · first admitted v29 · independently kernel and Lean verified; not Stable

Proof neighborhood

Direct dependencies

add_mul Stable theorem; checked-use authorized mul_add Stable theorem; checked-use authorized mul_assoc Stable theorem; checked-use authorized mul_comm Stable theorem; checked-use authorized add_assoc Stable theorem; checked-use authorized add_comm Stable theorem; checked-use authorized

Direct dependents

Formal native tactic body

Dependencies are introduced as named hypotheses before line 1. Local theorem links identify exact declared prerequisites. This exact body belongs to a complete independently kernel-checked constructive proof bundle and has Alpha checked-use authority; it does not imply Stable membership.

Read the argument

Proof checkpoints

14 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.

01Fix variables and assumptionsL1–9

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

  1. L1
    intro a
  2. L2
    intro b
  3. L3
    intro q
  4. L4
    intro r
  5. L5
    intro x
  6. L6
    intro y
  7. L7
    intro e
  8. L8
    intro ha
  9. L9
    intro he
02Calculate and transport equalitiesL10–11

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

  1. L10
    rewrite ha
  2. L11
    trans (b * q) * x + r * x
03Use earlier factsL12–12

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

  1. L12
    apply add_mul
04Calculate and transport equalitiesL13–14

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

  1. L13
    rewrite he
  2. L14
    simp [add_mul, mul_add, mul_assoc, mul_comm, add_assoc, add_comm]

Library-wide reading audit

Original exact command ledger · 14 lines
  1. 0001intro a
  2. 0002intro b
  3. 0003intro q
  4. 0004intro r
  5. 0005intro x
  6. 0006intro y
  7. 0007intro e
  8. 0008intro ha
  9. 0009intro he
  10. 0010rewrite ha
  11. 0011trans (b * q) * x + r * x
  12. 0012apply add_mul
  13. 0013rewrite he
  14. 0014simp [add_mul, mul_add, mul_assoc, mul_comm, add_assoc, add_comm]