OAI/Combinatorics/HoneycombChords/PathComponents.lean

GitHub source file

11 declarations, 0 contain sorry, 0 declared as axioms

Paths and cycles in finite two-port graphs

Formalized from Critical honeycomb chords with prescribed boundary endpoints (OpenAI, September 26, 2026).

  1. lemma OAI.CriticalHoneycomb.Transfer.PathComponents.ncard_neighbors line 22
  2. lemma OAI.CriticalHoneycomb.Transfer.PathComponents.ports_reachable line 26
  3. lemma OAI.CriticalHoneycomb.Transfer.PathComponents.path_neighbor_eq line 48
  4. lemma OAI.CriticalHoneycomb.Transfer.PathComponents.path_closed line 74
  5. lemma OAI.CriticalHoneycomb.Transfer.PathComponents.residual_isCycles line 85
  6. theorem OAI.CriticalHoneycomb.Transfer.PathComponents.path_and_cycles line 130

    Source documentation

    Every finite nonbranching two-port configuration is a path plus cycles. The path has no edge to the residual cycle graph.

    theorem path_and_cycles {a b : V} (hab : a ≠ b)
        (ha : G.degree a = 1) (hb : G.degree b = 1)
        (other : ∀ v, v ≠ a → v ≠ b → G.degree v = 0 ∨ G.degree v = 2) :
        ∃ p : G.Walk a b, p.IsPath ∧ (G \ p.toSubgraph.spanningCoe).IsCycles ∧
          ∀ v ∈ p.support, p.toSubgraph.neighborSet v = G.neighborSet v := by
    …

    Mentions: OAI.CriticalHoneycomb.Transfer.a, OAI.CriticalHoneycomb.Transfer.v

  7. def OAI.CriticalHoneycomb.Transfer.FiniteConfigurations.portRel line 154

    Source documentation

    The hard-wall two-port graph: the two exterior markers have only their prescribed incident edge; internal adjacency remains unchanged.

    def portRel (R : α → α → Prop) (a b : α) : (α ⊕ Bool) → (α ⊕ Bool) → Prop
      | .inl x, .inl y => R x y
      | .inr false, .inl y | .inl y, .inr false => y=a
      | .inr true, .inl y | .inl y, .inr true => y=b
      | .inr _, .inr _ => False

    Mentions: OAI.CriticalHoneycomb.Transfer.a

  8. lemma OAI.CriticalHoneycomb.Transfer.FiniteConfigurations.chain_snoc_ports line 160
  9. lemma OAI.CriticalHoneycomb.Transfer.FiniteConfigurations.chain_ports line 166
  10. lemma OAI.CriticalHoneycomb.Transfer.FiniteConfigurations.list_all_inl line 183
  11. lemma OAI.CriticalHoneycomb.Transfer.FiniteConfigurations.support_decomposition line 195