Circumference.lean`

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Annotation provenance. This overlay contains 10 curated AI-written annotations and 7190 mechanical source-derived annotations. They have not been human-reviewed as explanations; treat them as unverified and not mathematical authority. Retained generation history: The 71 original curated annotations were produced in a Claude Sonnet 5.5 session at medium effort; Claude Opus 5.5 is recorded in that session as the advisor model, not the direct author. The bulk source-derived expansion was generated mechanically from pinned source comments by tooling developed in a GPT-5.6 Sol session at ultra reasoning; GPT-5.6 Sol did not originate the quoted source prose. On 2026-10-17 the mechanically generated source-comment annotations of the Formal Conjectures, Carleson, FLT, PFR, CompFiles, Mathematics in Lean and Theorem Proving in Lean overlays were regenerated by the same generator after three corrections made in a Claude Sonnet 5.5 session: titles no longer cut a sentence inside mathematics or end on a dangling word, workflow markers are removed from the quoted prose, and declaration names follow the scanner's namespace resolution. The boilerplate step line was dropped, and comments that were only a row of dashes no longer yield annotations. No new prose was written and no human review is claimed.

Credit: The upstream authors and contributors retain credit for the project and mathematics. lean4-explainer only renders their pinned source and adds the separately disclosed explanation layer.

Project sources: Pinned project documentation, Formal Conjectures paper, arXiv v1

3 declarations, 0 contain sorry, 0 declared as axioms

Cycle lengths and circumference

The cycle lengths and the longest cycle length of a graph.

Imports (3)

Imported by 1 file

FormalConjecturesForMathlib.lean

def SimpleGraph.cycleLengths G.cycleLengths is the set of lengths of the cycles in G line 33 source
Source documentation
G.cycleLengths is the set of lengths of the cycles in G.

no axioms what this means
Statement uses: SimpleGraph, Set, Nat
Proof uses: Set.ofPred, Exists, SimpleGraph.Walk, And, SimpleGraph.Walk.IsCycle, Eq, SimpleGraph.Walk.length
```
def cycleLengths {α : Type*} (G : SimpleGraph α) : Set ℕ :=
…
```
def SimpleGraph.oddCycleLengths G.oddCycleLengths is the set of lengths of odd cycles in G line 37 source
Source documentation
G.oddCycleLengths is the set of lengths of odd cycles in G.

standard axioms: propext what this means
Statement uses: SimpleGraph, Set, Nat
Proof uses: Set.ofPred, And, Membership.mem, SimpleGraph.cycleLengths, Odd
2 instances, coercions and auxiliary constants left out.
```
def oddCycleLengths {α : Type*} (G : SimpleGraph α) : Set ℕ :=
…
```
def SimpleGraph.circumference circumference G is the length of the longest cycle in G line 44 source
Source documentation
circumference G is the length of the longest cycle in G. It is 0 when G is acyclic.

standard axioms: Classical.choice, Quot.sound, propext what this means
Statement uses: SimpleGraph, DecidableRel, SimpleGraph.Adj, Nat
Proof uses: SupSet.sSup, SimpleGraph.cycleLengths
1 instances, coercions and auxiliary constants left out.
```
noncomputable def circumference (G : SimpleGraph α) [DecidableRel G.Adj] : ℕ :=
…
```