[Turkmath:7390] ODTU-Bilkent Algebraic Geometry Seminar-Zoom-578

[Ali Sinan Sertöz]

*Welcome to the 2026 Spring talks of ODTÜ-Bilkent Algebraic Geometry 
Seminars**
*
/since 2000/
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This week the ODTÜ-Bilkent Algebraic Geometry Seminar 
<http://www.bilkent.edu.tr/~sertoz/agseminar.htm>  is *online*

/This talk will begin at _*15:40*__ (GMT+3)_/
Please check your time difference between Ankara and your city here 
<https://www.timeanddate.com/worldclock/fixedtime.html?msg=ODT%C3%9C-Bilkent+Algebraic+Geometry+Seminar&iso=20260220T1540&p1=19&ah=1>
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*

/Ben Viegers (1886-1947)
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**Speaker: Öznur Turhan <https://math.gsu.edu.tr/personel.html>**
******Affiliation: /Galatasaray & Polish Academy

/**
**Title:  Newton-nondegenerate line singularities, Lê numbers and Bekka 
(c)-regularity
**
**Abstract:** Consider an analytic function f(t,z) defined in a 
neighbourhood of the origin of C x Cn such that for all t, the function 
ft(z):=f(t,z) defines a hypersurface of Cn with a line singularity at 
0∈Cn . Denote by V(f) the hypersurface of C x Cn defined by f(t,z) and 
write Σf for its singular locus. We assume that ft is 
''quasi-convenient'' and Newton nondegenerate. Within this framework, we 
show that if the Lê numbers of ft are independent of t for all small t, 
then Σf is smooth and V(f)\Σf is Bekka (c)-regular over Σf. This is a 
version for line singularities of a result of Abderrahmane concerning 
isolated singularities.

As a corollary, we obtain that any family of quasi-convenient, Newton 
non-degenerate, line singularities with constant Lê numbers as above is 
topologically equisingular. In particular, this applies to families with 
non-constant Newton diagrams, and therefore extends, in some direction, 
a result previously observed by Damon.

This is a joint work with Christophe Eyral.

*Date: 20 February 2026, Friday*
*Time: 15:40 /(GMT+3)/*
*Place: **Zoom*

    /*Participants who have registered will receive the Zoom link via
    email one day before the seminar.*/

    /*If you registered for a previous talk in this series, there's no
    need to register again—you'll automatically receive the link for
    this session.*/

    /*If you haven't registered yet, please contact
    sertoz at bilkent.edu.tr to be added to the mailing list.*/

You are most cordially invited to attend.

Ali Sinan Sertöz

*/*/This seminar series is organized by a joint team from ODTÜ and Bilkent

Alexander Degtyarev (Bilkent)
Ali Sinan Sertöz (Bilkent) contact person
Ali Ulaş Özgür Kişisel (ODTÜ)
Yıldıray Ozan (ODTÜ)
/*/*

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Ali Sinan Sertöz
Bilkent University, Department of Mathematics, 06800 Ankara, Türkiye
Office: (90)-(312) - 290 1490
Department: (90)-(312) - 266 4377
e-mail:sertoz at bilkent.edu.tr <mailto:sertoz at bilkent.edu.tr> 
Web:sertoz.bilkent.edu.tr <http://sertoz.bilkent.edu.tr> 
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