Written on the Wall II - Conjecture 200 #
Reference: E. DeLaVina, Written on the Wall II, Conjectures of Graffiti.pc
theorem
WrittenOnTheWallII.GraphConjecture200.conjecture200
{α : Type u_1}
[Fintype α]
[DecidableEq α]
[Nontrivial α]
(G : SimpleGraph α)
(h : G.Connected)
(htree : ↑G.largestInducedTreeSize = ↑⌈1 + G.l⌉)
:
∃ (a : α) (b : α) (p : G.Walk a b), p.IsHamiltonian
WOWII Conjecture 200
For a simple connected graph G, if tree(G) = ⌈1 + l_avg(G)⌉, then G has a Hamiltonian path.
Here tree(G) is the number of vertices of a largest induced tree subgraph, and
l_avg(G) = averageIndepNeighbors G is the average over all vertices of the independence number
of the neighbourhood.
A Hamiltonian path is a walk visiting every vertex exactly once.