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Coloring linear orders with Rado's partial order
Author(s) -
Camerlo Riccardo,
Marcone Alberto
Publication year - 2007
Publication title -
mathematical logic quarterly
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.473
H-Index - 28
eISSN - 1521-3870
pISSN - 0942-5616
DOI - 10.1002/malq.200710002
Subject(s) - preorder , mathematics , countable set , combinatorics , order (exchange) , discrete mathematics , finance , economics
Let ⪯ R be the preorder of embeddability between countable linear orders colored with elements of Rado's partial order (a standard example of a wqo which is not a bqo). We show that ⪯ R has fairly high complexity with respect to Borel reducibility (e.g. if P is a Borel preorder, then P ≤ B ⪯ R ), although its exact classification remains open. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)