Andreas Weiermann

PROOF-THEORETIC RELATIONS BETWEEN HIGMAN’S AND KRUSKAL’S THEOREM, AND INDEPENDENCE RESULTS FOR TREE-LIKE STRUCTURES

Abstract Higman’s lemma and Kruskal’s theorem are two of the most celebrated results in the theory of well quasi-orders. In his seminal paper G. Higman obtained what is known as Higman’s lemma as a corollary of a more general theorem, dubbed here as Higman’s theorem. While the le...