 
Summary: Growth rates for subclasses of Av(321)
M. H. Albert1
, M. D. Atkinson1
, R. Brignall2
, N. Ruskuc3
,
Rebecca Smith4
, and J. West5
1Department of Computer Science, University of Otago
2Department of Mathematics and Statistics, The Open University
3School of Mathematics and Statistics, University of St Andrews
4Department of Mathematics, SUNY Brockport
5Heilbronn Institute for Mathematical Research, University of Bristol
Submitted: Jan 15, 2010; Accepted: Sep 27, 2010; Published: Oct 22, 2010
Mathematics Subject Classification: 05A05, 05A16
Abstract
Pattern classes which avoid 321 and other patterns are shown to have the same
growth rates as similar (but strictly larger) classes obtained by adding articulation
points to any or all of the other patterns. The method of proof is to show that the
elements of the latter classes can be represented as bounded merges of elements of
