Séminaires : Géométrie énumérative

Equipe(s) : aa,
Responsables :Penka Georgieva, Ilia Itenberg.
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Orateur(s) Eugenii Shustin - Tel Aviv University,
Titre Singular Welschinger invariants
Horaire10:00 à 11:00
RésumeWe discuss real enumerative invariants counting real deformations of plane curve singularities. A versal deformation base of a plane curve singularity contains local Severi varieties that parameterize deformations with a given delta-invariant. The local Severi varieties are analytic space germs and their (complex) multiplicities were computed by Beauville, Fantecci-Goettsche-van Straten, and Shende. For the equigeneric locus (local Severi variety corresponding to the maximal delta-invariant), a real multiplicity was introduced by Itenberg-Kharlamov-Sh. as a Welschinger-type signed count of certain equigeneric deformations. We show that similar real multiplicities can be defined for some other local Severi varieties as well as for all equiclassical loci (which count equigeneric deformations with a given number of cusps). We exhibit some examples and state open problems.