Journal of the London Mathematical Society Advance Access originally published online on October 18, 2007
Journal of the London Mathematical Society 2007 76(2):467-478; doi:10.1112/jlms/jdm059
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© 2007 London Mathematical Society
Unavoidable sigma-porous sets
Department of Mathematics
University College London
Gower Street
London
WC1E 6BT
United Kingdom
olga@math.ucl.ac.uk
Current address:
MathematicsInstitute
University of Warwick
Coventry
CV4 7AL
United Kingdom
We prove that every separable metric space which admits an
1-tree as a Lipschitz quotient has a
-porous subset which contains every Lipschitz curve up to a set of one-dimensional Hausdorff measure zero. This applies to any Banach space containing
1. We also obtain an infinite-dimensional counterexample to the Fubini theorem for the
-ideal of
-porous sets.
2000 Mathematics Subject Classification 28A05 (primary), 46B20, 46G99 (secondary).
The author was supported by the Marie Curie Intra-European Fellowship, contract no. MEIF-CT-2003-501214.
Received November 26, 2005; published online October 18, 2007.