Yevgeny Liokumovich
Contact information
Office at St George: BA6189
Office at UTM: DH3052
Email: ylio [at] math.toronto.edu
Teaching
Fall of 2024: MAT337 Introduction to Real Analysis,
Fall of 2024: MAT232 Multivariable Calculus.
Spring of 2024: MAT1341HS Topics in Differential Geometry: Manifolds with positive scalar curvature.
Fall of 2022: MAT337 Introduction to Real Analysis, MAT232 Multivariable Calculus.
Fall of 2021: MAT1300HF Differential Topology.
Fall of 2020: MAT337H1F Introduction to Real analysis.
Spring of 2020: MAT1309HS Geometric Inequalities.
Fall of 2019: MAT337H1F Introduction to Real analysis.
Upcoming talks
- Colloquium, Michigan State University. February 30, 2025
- Applications of minimal surfaces to geometry and topology of 3-manifolds, Geometric Analysis Student Seminar, April 21-22, https://wpd.ugr.es/~imag/events/event/geometric-analysis-student-seminar/
Seminars
I am a co-organizer of the Geometry and Topology Seminar and Fields Geometric Analysis Colloquium.
Students and postdocs
Current: Bruno Staffa (PhD student), Xinze Li (PhD student), Brendan Isley (PhD student), Talant Talipov (PhD student), Mitchell Gaudet (Master's student), Akashdeep
Dey (postdoc), Aleksandr Berdnikov (postdoc), Kennedy Idu
(postdoc), Lorenzo Sarnataro (postdoc).
Research
My interests lie at the
intersection of Geometric Analysis, Quantitative Topology, Geometric
Measure Theory, 3-manifold topology.
My research is supported by NSERC Discovery Grant, NSERC Accelerator
Award and Sloan Fellowship.
I'm new to mathematics. Can you explain your work to me?
Many of my results are applications of min-max methods to problems in geometry and topology.
Finding min-max is an optimization problem. The simplest optimization
problems that we learn from high school are finding minima and maxima.
It’s clear why these are important: a manager may want to maximize
profit and an engineer may want to minimize stress concentration in a
structure. Finding min-max is a somewhat more advanced optimization
problem. It is also sometimes called a "mountain pass problem" for the
following reason. Say, a group of tourists wants to get to the other
side of a mountain range in the easiest possible way. They are not
interested in climbing the peak of a mountain in the range, rather they
want to find a mountain pass. The problem of finding a mountain pass
can also be described as finding a path with the smallest possible
maximum elevation among all paths connecting two points on the two
sides of the range. In other words, we are trying to minimize a
maximum, hence the name “min-max”.
Min-max problems arise in many areas of science, such as machine
learning in Computer Science, differential equations, geometry, and
topology in Mathematics. An important problem of such kind in
differential geometry is the construction of minimal surfaces. Minimal
surfaces are generalizations of soap films or soap bubbles; using
min-max techniques one can show that they exist not only in our usual
space, but also in a very large class of spaces that can be defined
mathematically. Describing minimal surfaces like that makes them sound
exotic. Why would anyone study these objects? It turns out that they
can be used to prove many important results in mathematics and General
Relativity. The reason is because these “soap bubbles” can be used to
cut a complicated space into simpler pieces and also because they
capture important information about the space they lie in.
Papers
Most of my papers can be found on the arxiv.
“Length of a closed geodesic in 3-manifolds of positive scalar curvature” (with D. Maximo and R. Rotman), math arXiv:2504.05459
“Quantifying stability of non-power-seeking in artificial agents” (with E. R. Gunter and V. Krakovna), cs arXiv:2401.03529
“The Smale Conjecture and Min-Max Theory” (with D. Ketover), to appear in Inventiones mathematicae, math arXiv:2310.05756
“On the waist and width inequality in complete 3-manifolds with positive scalar curvature” (with Z. Wang), math arXiv:2308.04044
“Geodesic nets on non-compact Riemannian manifolds” (with. G.R. Chambers, A. Nabutovksy and R. Rotman), J. Reine Angew. Math.
“Parametric inequalities and Weyl law for the volume spectrum” (with L. Guth), Geom. Topol., math arXiv:2202.11805
“Generic density of geodesic nets” (with B. Staffa), Selecta Mathematica, math arXiv:2107.12340
“Classifying sufficiently connected PSC manifolds in 4 and 5 dimensions” (with O. Chodosh and C. Li), Geom. Topol., math arXiv:2105.07306
“Waist inequality for 3-manifolds with positive scalar curvature” (with D. Maximo), Perspectives in Scalar Curvature (Vol. 2), math arXiv:2012.12478
“Singular behavior and generic regularity of min-max minimal hypersurfaces” (with O. Chodosh and L. Spolaor), math arXiv:2007.11560
“On the existence of minimal Heegaard surfaces” (with D. Ketover and A. Song), math arXiv:1911.07161.
“Filling metric spaces” (with B. Lishak, A. Nabutovsky and R. Rotman), to appear in Duke Math. J., math arXiv:1905.06522
“On the existence of closed C^{1,1} curves of constant curvature” (with D. Ketover), math arXiv:1810.09308
“Area of convex disks” (with G.R. Chambers, C. Croke and H. Wen), Proc. Amer. Math. Soc., math arXiv:1701.06594
“Existence of minimal hypersurfaces in complete
manifolds of finite volume” (with G.R. Chambers), Invent. math. (2019), math arXiv:1609.04058
“Weyl law for the volume spectrum” (with F. C. Marques and A. Neves), Annals of Mathematics, Vol. 187 (2018), 933-961, math arXiv:1607.08721
“Determinantal variety and bilipschitz equivalence”
(with K.U. Katz, M.G. Katz and D. Kerner), J. Topol. Anal. Vol. 10,
No. 01, pp. 27-34 (2018), math arXiv:1602.01227
“Optimal sweepouts of a Riemannian 2-sphere” (with G.
R. Chambers), J. Eur. Math. Soc. 21 (2019), 1361-1377.
“Splitting a contraction of a simple curve traversed m
times” (with G. R. Chambers), J. Topol. Anal. Vol. 9, No. 3 (2017)
409–418.
“Lengths of three simple periodic geodesics on a
Riemannian 2-sphere” (with A. Nabutovsky and R. Rotman), Math. Ann.
(2017) 367:831–855.
“Width, Ricci curvature and minimal hypersurfaces” (with P. Glynn-Adey), J. Diff. Geom. Vol. 105 (2017), 33-54.
“Sweeping out 3-manifold of positive Ricci curvature by
short 1-cycles via estimates of min-max surfaces” (with X. Zhou), Int.
Math. Res. Not. (IMRN) (2016).
“Families of short cycles on Riemannian surfaces”, Duke Math. J. 165 (2016), no. 7, 1363-1379.
“Contracting the boundary of a Riemannian 2-disc” (with
A. Nabutovsky and R. Rotman), Geom. Funct. Anal. (GAFA), Vol. 25
(2015), 1543-1574.
“Slicing a 2-sphere”, J. Topol. Anal. Vol. 06 (2014), No. 04, 573-590.
“Converting homotopies to isotopies and dividing
homotopies in half in an effective way” (with G. R. Chambers), Geom.
Funct. Anal. (GAFA) Vol. 24 (2014), 1080-1100.
“Surfaces of small diameter with large width”, J. Topol. Anal. Vol. 06 (2014), No. 03, 383-396, 2013.
“Spheres of small diameter with long sweep-outs”, Proc. Amer. Math. Soc. 141 (2013), 309-312.
Personal
My wife Merey Ismailova is an artistic director of the Ismailova Theatre of Dance.