Journal of the London Mathematical Society Advance Access originally published online on May 10, 2009
Journal of the London Mathematical Society 2009 80(1):35-54; doi:10.1112/jlms/jdp006
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© 2009 London Mathematical Society
Approximation of definable sets by compact families, and upper bounds on homotopy and homology
Department of Mathematics
Purdue University
West Lafayette
IN 47907
USA
agabriel@math.purdue.edu
Department of Computer Science
University of Bath
Bath
BA2 7AY
United Kingdom
We prove new upper bounds on homotopy and homology groups of o-minimal sets in terms of their approximations by compact o-minimal sets. In particular, we improve the known upper bounds on Betti numbers of semialgebraic sets defined by quantifier-free formulae and obtain, for the first time, a singly exponential bound on Betti numbers of sub-Pfaffian sets.
2000 Mathematics Subject Classification 14P25 (primary), 14P15, 03C64 (secondary).
The first author was supported in part by NSF grant DMS-0801050.
Received October 18, 2007; revised October 15, 2008; published online May 10, 2009.