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 p n. exists D. (((p) = (n) + (D)) \/ ((n) = (p) + (D)))Constructive proof overview
Generated structural guide
Construct an actual natural absolute difference of every signed pair using constructive natural order.
The unchanged tactic script uses 3 declared prerequisites and contains 24 exact native proof lines.
Alpha v34 checked-use · first admitted v27 · independently kernel and Lean verified; not Stable
Proof neighborhood
Direct dependencies
le_or_lt Stable theorem; checked-use authorized lt_to_le Stable theorem; checked-use authorized add_comm Stable theorem; checked-use authorizedDirect 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
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 assumptionsL1–2
02Use earlier factsL3–4
03Separate the logical casesL5–6
04Construct an explicit witnessL7–7
Supply the displayed value, then prove that it has the required property.
- L7
exists x
05Separate the logical casesL8–8
Follow the explicit conjunction, disjunction, witness, or contradiction step recorded below.
- L8
right
06Calculate and transport equalitiesL9–10
07Use earlier factsL11–12
08Establish hreverseL13–17
Establish this local claim before using it. It is not an additional assumption. The following proof commands apply lt to le.
09Separate the logical casesL18–18
Follow the explicit conjunction, disjunction, witness, or contradiction step recorded below.
- L18
cases hreverse
10Construct an explicit witnessL19–19
Supply the displayed value, then prove that it has the required property.
- L19
exists x
11Separate the logical casesL20–20
Follow the explicit conjunction, disjunction, witness, or contradiction step recorded below.
- L20
left
12Calculate and transport equalitiesL21–22
Original exact command ledger · 24 lines
- 0001
intro p - 0002
intro n - 0003
specialize le_or_lt p - 0004
specialize le_or_lt n - 0005
cases le_or_lt - 0006
cases le_or_lt_left - 0007
exists x - 0008
right - 0009
trans x + p - 0010
symm - 0011
exact le_or_lt_left_witness - 0012
apply add_comm - 0013
have hreverse : exists mdr_gap_absolute_reverse. mdr_gap_absolute_reverse + (n) = (p) - 0014
specialize lt_to_le (n) - 0015
specialize lt_to_le (p) - 0016
apply lt_to_le - 0017
exact le_or_lt_right - 0018
cases hreverse - 0019
exists x - 0020
left - 0021
trans x + n - 0022
symm - 0023
exact hreverse_witness - 0024
apply add_comm