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The ultra‐weak Ash conjecture and some particular cases
Author(s) -
Chateau Annie,
More Malika
Publication year - 2006
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.200510010
Subject(s) - conjecture , mathematics , equivalence (formal languages) , spectrum (functional analysis) , collatz conjecture , combinatorics , pure mathematics , physics , quantum mechanics
Ash's functions N σ , k count the number of k ‐equivalence classes of σ ‐structures of size n . Some conditions on their asymptotic behavior imply the long standing spectrum conjecture. We present a new condition which is equivalent to this conjecture and we discriminate some easy and difficult particular cases. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)