On the local geometry of definably stratified sets

Date(s) : 16/02/2017   iCal
14 h 00 min - 15 h 00 min

With Guillaume Valette (IMPAN, Cracovie).

We prove that a 1985 theorem of Pawlucki, showing that Whitney regularity for a subanalytic set S with a smooth singular locus of codimension one implies that S is a finite union of C1 manifolds with boundary, applies to definable sets in polynomially bounded o-minimal structures. We give a refined version of Pawlucki’s theorem for arbitrary o-minimal structures, replacing Whitney (b)-regularity by a quantified version, and prove related results concerning normal cones and continuity of the density. We analyse two counterexamples to the extension of Pawlucki’s theorem to definable subsets in general o-minimal structures, and to several other statements valid for subanalytic sets.
In particular we give the first example of a Whitney (b)-regular definably stratified set for which the density is not continuous along a stratum.


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