From wqo to bqo, via Ellentuck's theorem
In this expository paper, first the theory of Ramsey subsets of reals is developed via Ellentuck's definitions and ideas. Then, after the introduction of well-quasi-ordered sets, a natural definition of better quasi-order is given along with a proof of Nash-Williams theorem that transfinite sequences from a bqo set form a bqo set.
scientific article; zbMATH DE number 97490
scientific article