theorem Graph.directSum_deleteVerts {α₁ : Type u_10} {α₂ : Type u_11} {β₁ : Type u_12} {β₂ : Type u_13} (G₁ : Graph α₁ β₁) (G₂ : Graph α₂ β₂) (X : Set (α₁ ⊕ α₂)) :
(G₁.directSum G₂).deleteVerts X = (G₁.deleteVerts (Sum.inl ⁻¹' X)).directSum (G₂.deleteVerts (Sum.inr ⁻¹' X))
theorem Graph.Preconnected.directEdgeSum_preconnected_right {α : Type u_1} {β₁ : Type u_10} {β₂ : Type u_11} {G₁ : Graph α β₁} {G₂ : Graph α β₂} (hG₁ : G₁.Preconnected) (hG₂ : G₂.vertexSet ⊆ G₁.vertexSet) :
(G₁.directEdgeSum G₂).Preconnected
theorem Graph.Preconnected.directEdgeSum_preconnected_left {α : Type u_1} {β₁ : Type u_10} {β₂ : Type u_11} {G₁ : Graph α β₁} {G₂ : Graph α β₂} (hG₂ : G₂.Preconnected) (hG₁ : G₁.vertexSet ⊆ G₂.vertexSet) :
(G₁.directEdgeSum G₂).Preconnected
Equations
- G.multiApex A = ((G.directSum (Graph.noEdge A Empty)).edgeMap (Sum.elim id Empty.elim) ⋯).directEdgeSum (Graph.completeBipartiteGraphOn G.vertexSet A)
Instances For
theorem Graph.multiApex_isLink_eq_match {α : Type u_1} {β : Type u_3} {G : Graph α β} {γ : Type u_10} {A : Set γ} :
(G.multiApex A).IsLink = fun (e : β ⊕ α × γ) (x y : α ⊕ γ) =>
match e, x, y with
| Sum.inl e, Sum.inl x, Sum.inl y => G.IsLink e x y
| Sum.inr (u, a), Sum.inl x, Sum.inr y => u ∈ G.vertexSet ∧ a ∈ A ∧ x = u ∧ y = a
| Sum.inr (u, a), Sum.inr x, Sum.inl y => u ∈ G.vertexSet ∧ a ∈ A ∧ y = u ∧ x = a
| x, x_1, x_2 => False
The graph with vertices V(G) ∪ {none} and edges E(G) ∪ V(G),
where the new edges go to the apex vertex.
Equations
Instances For
Alias of the reverse direction of Graph.apex_loopless_iff.
Alias of the reverse direction of Graph.apex_simple_iff.
theorem Graph.IsCyclicWalk.isCyclicWalk_apex {α : Type u_1} {β : Type u_3} {G : Graph α β} {C : WList α β} (hC : G.IsCyclicWalk C) :
G.apex.IsCyclicWalk (WList.edgeMap Sum.inl (WList.map some C))
theorem Graph.IsPath.isCyclicWalk_apex {α : Type u_1} {β : Type u_3} {G : Graph α β} {P : WList α β} (hP : G.IsPath P) (hPne : P.Nonempty) :
G.apex.IsCyclicWalk
((WList.cons none (Sum.inr P.first) (WList.edgeMap Sum.inl (WList.map some P))).concat (Sum.inr P.last) none)
Any nontrivial path in G can be extended to a cycle of G.apex via the apex.