Current library: Alpha v34, 4,223 checked-use theorems; Stable remains 432. Historical first admissions, original proof editions, and non-admitted aliases are preserved.
Canonical signed +1 is code 2 and -1 is code 1. The two-case unit graph does not assume an inverse or cancellation law: its actual product characterization and affine existence and uniqueness are proved. These scalar lemmas support the separately checked finite inverse criterion; full G009 remains broader.
Exact theorem in conservative defined notation
∀ r. ∀ u. ∀ e. ∀ a. ∀ b. ∀ c. ∀ d. SignedUnit(u) → SignedMul(a,u,b) → SignedAdd(r,b,e) → SignedMul(c,u,d) → SignedAdd(r,d,e) → a = c ∧ b = d
Every linked abbreviation expands hygienically to the identical original native formula.
Definition DAG
Actual proof prerequisites
Complete tactic proof in conservative notation
All 32 original proof lines are preserved. Only local proposition formulas are abbreviated; every abbreviation has an exact binder-safe expansion check. The linked exact edition contains the unchanged replay script.
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 assumptionsL1–10
02Fix variables and assumptionsL11–12
03Establish heqL13–20
Establish this local claim before using it. It is not an additional assumption. The following proof commands apply dirichlet signed add cancel left.
04Separate the logical casesL21–21
Follow the explicit conjunction, disjunction, witness, or contradiction step recorded below.
- L21
split
05Use earlier factsL22–27
Instantiate or apply named facts and discharge the corresponding proof obligations.
- L22
specialize dirichlet_signed_unit_multiply_cancel_right (u) - L23
specialize dirichlet_signed_unit_multiply_cancel_right (a) - L24
specialize dirichlet_signed_unit_multiply_cancel_right (c) - L25
specialize dirichlet_signed_unit_multiply_cancel_right (d) - L26
apply dirichlet_signed_unit_multiply_cancel_right - L27
exact hu
06Calculate and transport equalitiesL28–29
Original defined command ledger · 32 lines
- 0001
intro r - 0002
intro u - 0003
intro e - 0004
intro a - 0005
intro b - 0006
intro c - 0007
intro d - 0008
intro hu - 0009
intro hab - 0010
intro hbe - 0011
intro hcd - 0012
intro hde - 0013
have heq : b=d - 0014
specialize dirichlet_signed_add_cancel_left (r) - 0015
specialize dirichlet_signed_add_cancel_left (b) - 0016
specialize dirichlet_signed_add_cancel_left (d) - 0017
specialize dirichlet_signed_add_cancel_left (e) - 0018
apply dirichlet_signed_add_cancel_left - 0019
exact hbe - 0020
exact hde - 0021
split - 0022
specialize dirichlet_signed_unit_multiply_cancel_right (u) - 0023
specialize dirichlet_signed_unit_multiply_cancel_right (a) - 0024
specialize dirichlet_signed_unit_multiply_cancel_right (c) - 0025
specialize dirichlet_signed_unit_multiply_cancel_right (d) - 0026
apply dirichlet_signed_unit_multiply_cancel_right - 0027
exact hu - 0028
rewrite heq at hab - 0029
rewrite heq at hab - 0030
exact hab - 0031
exact hcd - 0032
exact heq