Well-Quasi Orders in Computation, Logic, Language and Reasoning: A Unifying Concept of Proof Theory, Automata Theory, Formal Languages and Descriptive Set TheoryPeter M. Schuster, Monika Seisenberger, Andreas Weiermann This book bridges the gaps between logic, mathematics and computer science by delving into the theory of well-quasi orders, also known as wqos. This highly active branch of combinatorics is deeply rooted in and between many fields of mathematics and logic, including proof theory, commutative algebra, braid groups, graph theory, analytic combinatorics, theory of relations, reverse mathematics and subrecursive hierarchies. As a unifying concept for slick finiteness or termination proofs, wqos have been rediscovered in diverse contexts, and proven to be extremely useful in computer science. The book introduces readers to the many facets of, and recent developments in, wqos through chapters contributed by scholars from various fields. As such, it offers a valuable asset for logicians, mathematicians and computer scientists, as well as scholars and students. |
Contents
1 | |
On Ordinal Invariants in Well Quasi Orders and Finite Antichain Orders | 29 |
The Ideal Approach to Computing Closed Subsets in WellQuasiorderings | 55 |
Strong WQO Tree Theorems | 107 |
Well Quasiorderings and Roots of Polynomials in a Hahn Field | 127 |
Upper Bounds on the Graph Minor Theorem | 145 |
Recent Progress on WellQuasiordering Graphs | 161 |
The Reverse Mathematics of wqos and bqos | 189 |
Well Quasiorders and the Functional Interpretation | 221 |
WellQuasi Orders and Hierarchy Theory | 271 |
A Combinatorial Bound for a Restricted Form of the Termination Theorem | 321 |
A Mechanized Proof of Higmans Lemma by Open Induction | 339 |
WellPartial Orderings and their Maximal Order Types | 351 |