ODTÜ-BİLKENT Algebraic
Geometry Seminar
(See all past talks ordered according
to speaker or date)
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**** 2026 Fall Talks ****
This
semester we plan to have all of our seminars online
Demir Eken - [Michigan] - Positivity, Adjoint Linear Systems, and Jet
Separation
| Abstract: Positivity of
line bundles allows us to construct morphisms and
projective embeddings, and more generally global
sections with prescribed Taylor coefficients. This
raises a quantitative question: how much
positivity is needed for global generation, very
ampleness, or separation of higher-order jets? In
this expository talk, I will discuss these
questions for adjoint line bundles $K_X+mA$ with
$A$ ample, starting from Fujita’s conjectures. I
will also present global and local criteria for
$k$-jet separation and the role of Seshadri
constants in measuring local positivity. |
Anatoly Libgober - [UIC] - Pencils on curves on algebraic surfaces with reducible fibers
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Abstract: We describe
constraints on the pencils of curves having
sufficiently many reducible members, depending on
the surface and the numerical classes of
irreducible components. In the case of pencils of
curves in linear systems with a small degree of
the discriminant we give a classification of these
pencils. This follows from the description of
polarized simply connected surfaces with the
degree of discriminant less than 13. |
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Abstract: Upon completing the
deformation classification of simple real
plane sextic curves with smooth real part,
we observed certain distinctive lacunas in
our list of topological types. These lacunas
are very similar to those in the smooth
case, which originally led to the discovery
of the Gudkov--Rokhlin congruence. However,
ours depend on the set of singularities and,
therefore, need a new dedicated congruence;
we suggest one. |
ODTÜ talks are either at Hüseyin Demir Seminar room
or at Gündüz İkeda seminar room at
the Mathematics building of ODTÜ.
Bilkent talks are at room 141 of Faculty of
Science A-building at Bilkent.
Zoom talks are online.
Talks of previous
years
