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 a b c. (exists k. k + S a = b) -> (exists k. k + S b = c) -> exists k. k + S a = cStructural proof guide
Strict order is transitive.
Direct prerequisites: add_assoc, add_succ_left. The authored body proceeds by case analysis (2).
Proof neighborhood
Direct dependencies
Direct dependents
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
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 (2)
01Fix variables and assumptionsL1–5
02Separate the logical casesL6–7
03Construct an explicit witnessL8–8
Supply the displayed value, then prove that it has the required property.
- L8
exists x1 + S x
04Calculate and transport equalitiesL9–9
Carry out the recorded arithmetic or equality steps; inspect the exact commands for their direction and premises.
- L9
trans x1 + (S x + S a)
05Use earlier factsL10–10
Instantiate or apply named facts and discharge the corresponding proof obligations.
- L10
apply add_assoc
06Calculate and transport equalitiesL11–13
07Use earlier factsL14–14
Instantiate or apply named facts and discharge the corresponding proof obligations.
- L14
apply add_succ_left
08Calculate and transport equalitiesL15–18
Original exact command ledger · 20 lines
- 0001
intro a - 0002
intro b - 0003
intro c - 0004
intro hab - 0005
intro hbc - 0006
cases hab - 0007
cases hbc - 0008
exists x1 + S x - 0009
trans x1 + (S x + S a) - 0010
apply add_assoc - 0011
trans x1 + S (x + S a) - 0012
congr - 0013
refl - 0014
apply add_succ_left - 0015
trans x1 + S b - 0016
congr - 0017
refl - 0018
congr - 0019
exact hab_witness - 0020
exact hbc_witness