The Theory of Well-Quasi-Ordering: A Frequently Discovered Concept

@article{Kruskal1972TheTO,
  title={The Theory of Well-Quasi-Ordering: A Frequently Discovered Concept},
  author={Joseph B. Kruskal},
  journal={J. Comb. Theory, Ser. A},
  year={1972},
  volume={13},
  pages={297-305}
}
Results from the rich and well-developed theory of well-quasi-ordering have often been rediscovered and republished. The purpose of this paper is to describe this intriguing subject. To illustrate the theory, here are two definitions and an elementary result. A partially ordered set is called well-partially-ordered if every subset has at least one, but only a finite number, of minimal elements. For sequences s and t, we define s < t if some subsequence of t majorizes s term by term. Then the… CONTINUE READING