134
Voted
JCT
2011
15 years 17 days ago
2011
Two non-isomorphic graphs are twins if each is isomorphic to a subgraph of the other. We prove that a rayless graph has either infinitely many twins or none.
145
Voted
COMBINATORICA
2010
15 years 18 days ago
2010
We prove that every rayless graph has an unfriendly partition.