caa a22 4500 386384924 CHVBK 20180307112055.0 cr unu---uuuuu 161130e198909 xx s 000 0 eng 10.1017/S0305004100078075 doi S0305004100078075 pii (NATIONALLICENCE)cambridge-10.1017/S0305004100078075 Kříž Igor The Ohio State University, Department of Mathematics, Columbus, Ohio 43210, U.S.A. Proving a witness lemma in better-quasiordering theory: the method of ‘extensions' [Elektronische Daten] [Igor Kříž] We introduce a new method for proving ‘witness lemmas' in BQO theory. As an application, we obtain witness-lemmas for arbitrary trees and for σ-scattered linear orderings. A positive answer to a question by Van Engelen, Miller and Steel follows. Copyright © Cambridge Philosophical Society 1989 Mathematical Proceedings of the Cambridge Philosophical Society Cambridge University Press 106/2(1989-09), 253-262 0305-0041 106:2<253 1989 106 PSP https://doi.org/10.1017/S0305004100078075 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1017/S0305004100078075 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Kříž Igor The Ohio State University, Department of Mathematics, Columbus, Ohio 43210, U.S.A NATIONALLICENCE 773 0- Mathematical Proceedings of the Cambridge Philosophical Society Cambridge University Press 106/2(1989-09), 253-262 0305-0041 106:2<253 1989 106 PSP CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge