Properties of the ends of graphs #
This file is meant to contain results about the ends of (locally finite connected) graphs.
instance
SimpleGraph.instIsEmptyElemForallObjOppositeFinsetComponentComplFunctorEndOfFinite
{V : Type}
(G : SimpleGraph V)
[Finite V]
:
IsEmpty ↑G.end
theorem
SimpleGraph.end_componentCompl_infinite
{V : Type}
(G : SimpleGraph V)
(e : ↑G.end)
(K : (Finset V)ᵒᵖ)
:
(SimpleGraph.ComponentCompl.supp (↑e K)).Infinite
The componentCompl
s chosen by an end are all infinite.
instance
SimpleGraph.compononentComplFunctor_nonempty_of_infinite
{V : Type}
(G : SimpleGraph V)
[Infinite V]
(K : (Finset V)ᵒᵖ)
:
Nonempty (G.componentComplFunctor.obj K)
instance
SimpleGraph.componentComplFunctor_finite
{V : Type}
(G : SimpleGraph V)
[G.LocallyFinite]
[Fact G.Preconnected]
(K : (Finset V)ᵒᵖ)
:
Finite (G.componentComplFunctor.obj K)
theorem
SimpleGraph.nonempty_ends_of_infinite
{V : Type}
(G : SimpleGraph V)
[G.LocallyFinite]
[Fact G.Preconnected]
[Infinite V]
:
G.end.Nonempty
A locally finite preconnected infinite graph has at least one end.