BT007V

beta_repeat_succ_extend

Stable checked-use theorem · independently kernel verified

Recode a constant prefix and append one more copy of its value.

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 b c a l sl. sl = S l -> (forall ff_i_before. (exists ff_lt_before_bound. ff_lt_before_bound + S ff_i_before = l) -> (((exists ff_h_before_decoded. ff_h_before_decoded + S (a) = S ((S (ff_i_before)) * c)) /\ exists ff_q_before_decoded. b = ff_q_before_decoded * S ((S (ff_i_before)) * c) + (a)))) -> exists z d. (forall ff_i_after. (exists ff_lt_after_bound. ff_lt_after_bound + S ff_i_after = sl) -> (((exists ff_h_after_decoded. ff_h_after_decoded + S (a) = S ((S (ff_i_after)) * d)) /\ exists ff_q_after_decoded. z = ff_q_after_decoded * S ((S (ff_i_after)) * d) + (a))))

Structural proof guide

Recode a constant prefix and append one more copy of its value.

Direct prerequisites: beta_prefix_extend, le_of_succ_le_succ, le_eq_or_lt. The authored body proceeds by case analysis (4), intermediate claims (2), equality transport (3).

Proof neighborhood

Direct dependencies

BT005D beta_prefix_extend BT0017 le_of_succ_le_succ BT001C le_eq_or_lt

Direct dependents

BT007W beta_repeat_exists

Formal native tactic body

Dependencies are hypotheses of the historical Alpha-v12 body receipt. The complete historical Alpha-v18 proof bundle independently checks every dependency; current Alpha v25 preserves that checked theorem use without changing Stable membership.

Read the argument

Proof checkpoints

40 script commands · 11 reading checkpoints · 2 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.

Named ingredients (3)
beta prefix extendle of succ le succle eq or lt
01Fix variables and assumptionsL1–7

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

  1. L1
    intro b
  2. L2
    intro c
  3. L3
    intro a
  4. L4
    intro l
  5. L5
    intro sl
  6. L6
    intro hsl
  7. L7
    intro hrepeat
02Use earlier factsL8–11

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

  1. L8
    specialize beta_prefix_extend l
  2. L9
    specialize beta_prefix_extend b
  3. L10
    specialize beta_prefix_extend c
  4. L11
    specialize beta_prefix_extend a
03Separate the logical casesL12–14

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

  1. L12
    cases beta_prefix_extend
  2. L13
    cases beta_prefix_extend_witness
  3. L14
    cases beta_prefix_extend_witness_witness
04Construct an explicit witnessL15–16

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

  1. L15
    exists x
  2. L16
    exists x1
05Fix variables and assumptionsL17–18

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

  1. L17
    intro i
  2. L18
    intro hi
06Calculate and transport equalitiesL19–19

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

  1. L19
    rewrite hsl at hi
07Establish hilL20–24

Establish this local claim before using it. It is not an additional assumption. The following proof commands apply le of succ le succ.

  1. L20
    have hil : exists h. h + i = l
  2. L21
    specialize le_of_succ_le_succ i
  3. L22
    specialize le_of_succ_le_succ l
  4. L23
    apply le_of_succ_le_succ
  5. L24
    exact hi
08Establish hsplitL25–29

Establish this local claim before using it. It is not an additional assumption. The following proof commands apply le eq or lt.

  1. L25
    have hsplit : i = l \/ exists h. h + S i = l
  2. L26
    specialize le_eq_or_lt i
  3. L27
    specialize le_eq_or_lt l
  4. L28
    apply le_eq_or_lt
  5. L29
    exact hil
09Separate the logical casesL30–30

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

  1. L30
    cases hsplit
10Calculate and transport equalitiesL31–32

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

  1. L31
    rewrite hsplit_left
  2. L32
    rewrite hsplit_left
11Use earlier factsL33–40

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

  1. L33
    exact beta_prefix_extend_witness_witness_left
  2. L34
    specialize beta_prefix_extend_witness_witness_right i
  3. L35
    specialize beta_prefix_extend_witness_witness_right a
  4. L36
    apply beta_prefix_extend_witness_witness_right
  5. L37
    exact hsplit_right
  6. L38
    specialize hrepeat i
  7. L39
    apply hrepeat
  8. L40
    exact hsplit_right

Library-wide reading audit

Original exact command ledger · 40 lines
  1. 0001intro b
  2. 0002intro c
  3. 0003intro a
  4. 0004intro l
  5. 0005intro sl
  6. 0006intro hsl
  7. 0007intro hrepeat
  8. 0008specialize beta_prefix_extend l
  9. 0009specialize beta_prefix_extend b
  10. 0010specialize beta_prefix_extend c
  11. 0011specialize beta_prefix_extend a
  12. 0012cases beta_prefix_extend
  13. 0013cases beta_prefix_extend_witness
  14. 0014cases beta_prefix_extend_witness_witness
  15. 0015exists x
  16. 0016exists x1
  17. 0017intro i
  18. 0018intro hi
  19. 0019rewrite hsl at hi
  20. 0020have hil : exists h. h + i = l
  21. 0021specialize le_of_succ_le_succ i
  22. 0022specialize le_of_succ_le_succ l
  23. 0023apply le_of_succ_le_succ
  24. 0024exact hi
  25. 0025have hsplit : i = l \/ exists h. h + S i = l
  26. 0026specialize le_eq_or_lt i
  27. 0027specialize le_eq_or_lt l
  28. 0028apply le_eq_or_lt
  29. 0029exact hil
  30. 0030cases hsplit
  31. 0031rewrite hsplit_left
  32. 0032rewrite hsplit_left
  33. 0033exact beta_prefix_extend_witness_witness_left
  34. 0034specialize beta_prefix_extend_witness_witness_right i
  35. 0035specialize beta_prefix_extend_witness_witness_right a
  36. 0036apply beta_prefix_extend_witness_witness_right
  37. 0037exact hsplit_right
  38. 0038specialize hrepeat i
  39. 0039apply hrepeat
  40. 0040exact hsplit_right