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On Q-Fano 3-folds of Fano index 2
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Prokhorov Y., Reid M.
Let X be a Q-Fano 3-fold of rank 1 with qQ(X)=qF(X)=2 and KX not Cartier. Let A be a Weil divisor on X such that −KX = 2A. Then dim |A| ≤ 4. Moreover, if dim |A| = 4, then X belongs to the single irreducible family.
In book
Vol. 70: Minimal Models and Extremal Rays. , Kyoto : Mathematical Society of Japan, 2016
Coates T., Corti A., Galkin S. et al., Geometry and Topology 2016 Vol. 20 No. 1 P. 103-256
The quantum period of a variety X is a generating function for certain Gromov-Witten invariants of X which plays an important role in mirror symmetry. In this paper we compute the quantum periods of all 3-dimensional Fano manifolds. In particular we show that 3-dimensional Fano manifolds with very ample anticanonical bundle have mirrors given by ...
Added: November 18, 2014
Prokhorov Y., Kuznetsov A., Shramov K., Japanese Journal of Mathematics 2018 Vol. 13 No. 1 P. 109-185
We discuss various results on Hilbert schemes of lines and conics and automorphism groups of smooth Fano threefolds of Picard rank 1. Besides a general review of facts well known to experts, the paper contains some new results, for instance, we give a description of the Hilbert scheme of conics on any smooth Fano threefold ...
Added: November 22, 2017
Prokhorov Y., Advances in Geometry 2013 Vol. 13 No. 3 P. 419-434
We classify Fano threefolds with only Gorenstein terminal singularities and Picard
number greater than 1, satisfying the additional assumption that the G-invariant part of the Weil
divisor class group is of rank 1 with respect to an action of some group G. ...
Added: October 7, 2013
Galkin S., Golyshev V., Iritani H., / Cornell University. Series math "arxiv.org". 2014. No. 1404.6407.
We propose Gamma Conjectures for Fano manifolds which can be thought of as a square root of the index theorem. Studying the exponential asymptotics of solutions to the quantum differential equation, we associate a principal asymptotic class A_F to a Fano manifold F. We say that F satisfies Gamma Conjecture I if A_F equals the ...
Added: May 4, 2014
Galkin S., Iritani H., , in : Primitive Forms and Related Subjects — Kavli IPMU 2014. : Tokyo : Mathematical Society of Japan, 2019. P. 55-115.
The asymptotic behaviour of solutions to the quantum differential equation of a Fano manifold F defines a characteristic class A_F of F, called the principal asymptotic class.
Gamma conjecture of Vasily Golyshev and the present authors claims that the principal asymptotic class A_F equals the Gamma class associated to Euler's Gamma-function.
We illustrate in the case of ...
Added: September 1, 2018
Yuri Prokhorov, Documenta Mathematica 2010 Vol. 15 P. 843-872
We study Q-Fano threefolds of large Fano index. In
particular, we prove that the maximum possible Fano index is attained
only by the weighted projective space P(3,4,5,7). ...
Added: December 6, 2013
Akhtar M., Coates T., Galkin S. et al., Symmetry, Integrability and Geometry: Methods and Applications (SIGMA) 2012 Vol. 8 No. 094 P. 1-707
Given a Laurent polynomial f, one can form the period of f: this is a function of one complex variable that plays an important role in mirror symmetry for Fano manifolds. Mutations are a particular class of birational transformations acting on Laurent polynomials in two variables; they preserve the period and are closely connected with ...
Added: September 14, 2013
Kishimoto T., Yuri Prokhorov, Zaidenberg M., Osaka Journal of Mathematics 2014 Vol. 51 No. 4 P. 1093-1113
We address the following question: When an affine cone over a smooth Fano threefold admits an effective action of the additive group? In this paper we deal with Fano threefolds of index 1 and Picard number 1. Our approach is based on a geometric criterion from our previous paper, which relates the existence of an ...
Added: October 10, 2013
Przyjalkowski V., Shramov K., Communications in Number Theory and Physics 2020 Vol. 14 No. 3 P. 511-553
We prove that if a smooth variety with non-positive canonical class can be embedded into a weighted projective space of dimension n as a well formed complete intersection and it is not an intersection with a linear cone therein, then the weights of the weighted projective space do not exceed n+1. Based on this bound ...
Added: October 13, 2020
Kuznetsov A., Debarre O., / Cornell University. Series math "arxiv.org". 2015.
This paper performs a systematic study of Gushel–Mukai varieties—Fano manifolds with Picard number 1, coindex 3, and degree 10 (higher-dimensional analogues of prime Fano threefolds of genus 6). We introduce a new approach to the classification of these varieties which includes mildly singular varieties, gives a criterion for an isomorphism of such varieties, and describes ...
Added: November 15, 2015
Kuznetsov A., Central European Journal of Mathematics 2012 Vol. 10 No. 4 P. 1198-1231
We introduce the notion of an instanton bundle on a Fano threefold of index 2. For such bundles we give an analogue of a monadic description and discuss the curve of jumping lines. The cases of threefolds of degree 5 and 4 are considered in a greater detail. ...
Added: September 10, 2012
Fonarev A., Kuznetsov A., / Cornell University. Series arXiv "math". 2016.
We prove that the derived category D(C) of a generic curve of genus greater than one embeds into the derived category D(M) of the moduli space M of rank two stable bundles on C with fixed determinant of odd degree. ...
Added: April 10, 2017
Galkin S., Shinder E., / Cornell University. Series math "arxiv.org". 2014. No. 1405.5154.
We find a relation between a cubic hypersurface Y and its Fano variety of lines F(Y) in the Grothendieck ring of varieties. We prove that if the class of an affine line is not a zero-divisor in the Grothendieck ring of varieties, then Fano variety of lines on a smooth rational cubic fourfold is birational ...
Added: May 21, 2014
Cheltsov Ivan, Shramov Constantin, Experimental Mathematics 2013 Vol. 22 No. 3 P. 313-326
We study del Pezzo surfaces that are quasismooth and well-formed weighted hypersurfaces. In particular, we find all such surfaces whose α-invariant of Tian is greater than 2/3. ...
Added: January 27, 2014
Cheltsov I., Przyjalkowski V., Shramov K., European Journal of Mathematics 2016 Vol. 2 No. 1 P. 96-119
We study quartic double solids admitting icosahedral symmetry. ...
Added: December 3, 2015
Ю. Г. Прохоров, Известия РАН. Серия математическая 2013 Т. 77 № 3 С. 199-222
We study elements $\tau$ of order two in the birational automorphism groups of rationally connected three-dimensional algebraic varieties such that there exists a non-uniruled divisorial component of the $\tau$-fixed point locus. Using the equivariant minimal model program, we give a rough classification of such elements. ...
Added: July 1, 2013
Prokhorov Y., Zaidenberg M., , in : Advanced Studies in Pure Mathematics. Vol. 75: Algebraic Varieties and Automorphism Groups.: Tokyo : American Mathematical Society, World Scientific, 2017. P. 443-463.
We produce new families of smooth Fano fourfolds with Picard rank 1, which contain cylinders, i.e., Zariski open subsets of form Z × A 1 , where Z is a quasiprojective variety. The affine cones over such a fourfold admit effective G a -actions. Similar constructions of cylindrical Fano threefolds and fourfolds were done previously ...
Added: August 1, 2017
Galkin S., / Cornell University. Series math "arxiv.org". 2018. No. 1809.02705.
We classify smooth Fano threefolds that admit degenerations to toric Fano threefolds with ordinary double points. ...
Added: September 25, 2018
Galkin S., / Cornell University. Series math "arxiv.org". 2014. No. 1404.7388.
Consider a Laurent polynomial with real positive coefficients such that the origin is strictly inside its Newton polytope. Then it is strongly convex as a function of real positive argument. So it has a distinguished Morse critical point --- the unique critical point with real positive coordinates. As a consequence we obtain a positive answer ...
Added: May 4, 2014
Coates T., Galkin S., Kasprzyk A. et al., / Cornell University. Series math "arxiv.org". 2014. No. 1406.4891.
We collect a list of known four-dimensional Fano manifolds and compute their quantum periods. This list includes all four-dimensional Fano manifolds of index greater than one, all four-dimensional toric Fano manifolds, all four-dimensional products of lower-dimensional Fano manifolds, and certain complete intersections in projective bundles. ...
Added: June 20, 2014
Coates T., Corti A., Galkin S. et al., , in : European Congress of Mathematics Kraków, 2 – 7 July, 2012. : Zürich : European Mathematical Society Publishing house, 2014. Ch. 16. P. 285-300.
We consider mirror symmetry for Fano manifolds, and describe how one can recover the classification of 3-dimensional Fano manifolds from the study of their mirrors. We sketch a program to classify 4-dimensional Fano manifolds using these ideas. ...
Added: February 19, 2014
Prokhorov Y., Advances in Geometry 2013 Vol. 13 No. 3 P. 389-418
We classify Fano threefolds with only terminal singularities whose canonical class is
Cartier and divisible by 2 with the additional assumption that the G-invariant part of the Weil divisor
class group is of rank 1 with respect to an action of some group G. In particular, we find a lot of
examples of Fano 3-folds with “many” symmetries. ...
Added: October 7, 2013
Prokhorov Y., Zaidenberg M., European Journal of Mathematics 2016 Vol. 2 No. 1 P. 262-282
We construct four different families of smooth Fano fourfolds with Picard rank 1, which contain cylinders, i.e., Zariski open subsets of the form Z ×A1, where Z is a quasiprojective variety. The affine cones over such a fourfold admit effective Ga-actions. Similar constructions of cylindrical Fano threefolds were done previously in the papers by Kishimoto ...
Added: November 27, 2015
Prokhorov Y., Kuznetsov A., / Cornell University. Series arXiv "math". 2017.
We give an explicit construction of prime Fano threefolds of genus 12 with a G_m-action, describe their isomorphism classes and automorphism groups. ...
Added: November 29, 2017