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BEGIN:VEVENT
SUMMARY:Andrea Mondino (University of Oxford)
DTSTART:20200921T133000Z
DTEND:20200921T143000Z
DTSTAMP:20260404T095827Z
UID:UofT_GandT/1
DESCRIPTION:Title: <a href="https://stable.researchseminars.org/talk/UofT_
 GandT/1/">An optimal transport formulation of the Einstein equations of ge
 neral relativity</a>\nby Andrea Mondino (University of Oxford) as part of 
 University of Toronto Geometry & Topology seminar\n\n\nAbstract\nIn the se
 minar I will present a recent work joint with S. Suhr (Bochum) giving an o
 ptimal transport formulation of the full Einstein equations of general rel
 ativity\, linking the (Ricci) curvature of a space-time with the cosmologi
 cal constant and the energy-momentum tensor. Such an optimal transport for
 mulation is in terms of convexity/concavity properties of the Shannon-Bolz
 mann entropy along curves of probability measures extremizing suitable opt
 imal transport costs. The result\, together with independent work by McCan
 n on lower bounds for Lorentzian Ricci Curvature\, gives a new connection 
 between general relativity and optimal transport\; moreover it gives a mat
 hematical reinforcement of the strong link between general relativity and 
 thermodynamics/information theory that emerged in the physics literature o
 f the last years.\n\nThe talk will be via Zoom at: https://us02web.zoom.us
 /j/81133134160 passcode 507121\n
LOCATION:https://stable.researchseminars.org/talk/UofT_GandT/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Qin Deng (University of Toronto)
DTSTART:20201005T201000Z
DTEND:20201005T210000Z
DTSTAMP:20260404T095827Z
UID:UofT_GandT/2
DESCRIPTION:Title: <a href="https://stable.researchseminars.org/talk/UofT_
 GandT/2/">Hölder continuity of tangent cones in RCD(K\,N) spaces and appl
 ications to non-branching</a>\nby Qin Deng (University of Toronto) as part
  of University of Toronto Geometry & Topology seminar\n\n\nAbstract\nIt is
  known by a result of Colding-Naber that for any two points in a Ricci lim
 it space\, there exists a minimizing geodesic where the geometry of small 
 balls centred along the interior of the geodesic change in at most a H\\
 ”older continuous manner. This was shown using an extrinsic argument and
  had several key applications for the structure theory of Ricci limits. In
  this talk\, I will discuss how to generalize this result to the setting o
 f metric measure spaces satisfying the synthetic lower Ricci curvature bou
 nd condition RCD(K\,N). As an application\, I will show that all RCD(K\,N)
  spaces are non-branching\, a fact which was previously unknown for Ricci 
 limits.\n
LOCATION:https://stable.researchseminars.org/talk/UofT_GandT/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Aleksandr Berdnikov (MIT)
DTSTART:20201012T200000Z
DTEND:20201012T210000Z
DTSTAMP:20260404T095827Z
UID:UofT_GandT/3
DESCRIPTION:Title: <a href="https://stable.researchseminars.org/talk/UofT_
 GandT/3/">Waists of maps measured via Urysohn width</a>\nby Aleksandr Berd
 nikov (MIT) as part of University of Toronto Geometry & Topology seminar\n
 \n\nAbstract\nUrysohn d-width is a measure for estimating how close a metr
 ic space $X$ is to being $d$-dimensional. Specifically\, $UW_d(X)$ is the 
 lower bound for the largest fiber of a projection of $X$ to a $d$-dimensio
 nal complex. However\, the dimension estimated in such a way is less well-
 behaved than the usual dimension. We explore this discrepancy getting resu
 lts like the following:\n\n1. The topological projection $B^{f}\\times B^m
 \\to B^m$ with $f\\sim mk$ can have a metric\, such that $UW_{m+k}(F)<\\va
 repsilon$ for all fibers $F$\, and yet the total space has $UW_{f-1}=O(1)$
  (``almost $m+k$ dimensional fibers over $m$-base build a $\\sim mk$-space
 '').\n\n2. On the other hand\, for a map $X\\to Y^m$ the $UW_{m+1}(X)$  is
  bounded by $UW_1$ and $rk (H_1(\\cdot\,\\mathbb{Z}/2))$ of the fibers.\n\
 n Joint with Alexey Balitskiy.\n\nhttps://utoronto.zoom.us/j/82235760196\n
LOCATION:https://stable.researchseminars.org/talk/UofT_GandT/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nick Salter (Columbia University)
DTSTART:20201019T200000Z
DTEND:20201019T210000Z
DTSTAMP:20260404T095827Z
UID:UofT_GandT/4
DESCRIPTION:Title: <a href="https://stable.researchseminars.org/talk/UofT_
 GandT/4/">The “what” and the “why” of framed mapping class groups<
 /a>\nby Nick Salter (Columbia University) as part of University of Toronto
  Geometry & Topology seminar\n\n\nAbstract\nGiven a family of Riemann surf
 aces\, the monodromy representation\, valued in the mapping class group of
  the fiber\, is a key invariant that encodes a great deal of information a
 bout the topological and algebraic structure of the family. Many natural f
 amilies\, including families of translation surfaces\, smooth sections of 
 line bundles on surfaces (e.g. plane curves)\, and the family of Milnor fi
 bers of a plane curve singularity\, are equipped with the additional data 
 of a preferred section of a line bundle (e.g. a holomorphic 1-form). In su
 ch circumstances\, the monodromy group is valued in a special subgroup kno
 wn as the framed mapping class group. I will discuss some new tools to und
 erstand framed mapping class groups\, and the sorts of insight they can br
 ing to the study of the families listed above. This encompasses joint work
  with Aaron Calderon and Pablo Portilla Cuadrado.\n
LOCATION:https://stable.researchseminars.org/talk/UofT_GandT/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yi Lai (UC Berkley)
DTSTART:20201026T200000Z
DTEND:20201026T210000Z
DTSTAMP:20260404T095827Z
UID:UofT_GandT/5
DESCRIPTION:Title: <a href="https://stable.researchseminars.org/talk/UofT_
 GandT/5/">A family of 3d steady gradient solitons that are flying wings</a
 >\nby Yi Lai (UC Berkley) as part of University of Toronto Geometry & Topo
 logy seminar\n\n\nAbstract\nA family of 3d steady gradient solitons that a
 re flying wings\nAbstract: We found a family of $\\mathbb{Z}_2\\times O(2)
 $-symmetric 3d steady gradient Ricci solitons. We show that these solitons
  are all flying wings. This confirms a conjecture by Hamilton.\n\nhttps://
 us02web.zoom.us/j/89431825216 Passcode: 569079\n
LOCATION:https://stable.researchseminars.org/talk/UofT_GandT/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Zhichao Wang (University of Toronto Mississauga)
DTSTART:20201102T210000Z
DTEND:20201102T220000Z
DTSTAMP:20260404T095827Z
UID:UofT_GandT/6
DESCRIPTION:Title: <a href="https://stable.researchseminars.org/talk/UofT_
 GandT/6/">Multiplicity one for min-max theory in compact manifolds with bo
 undary and its applications</a>\nby Zhichao Wang (University of Toronto Mi
 ssissauga) as part of University of Toronto Geometry & Topology seminar\n\
 n\nAbstract\nIn this talk\, we introduce the multiplicity one theorem for 
 min-max free boundary minimal hypersurfaces in compact manifolds with boun
 dary of dimension between 3 and 7 for generic metrics. To approach this\, 
 we developed the min-max theory for free boundary h-hypersurfaces and prov
 ed the generic properness for free boundary minimal hypersurfaces. The app
 lication includes the construction of new free boundary minimal hypersurfa
 ces in the unit balls in Euclidean spaces and self-shrinkers of the mean c
 urvature flow with arbitrarily large entropy. This is a joint work with A.
  Sun and X. Zhou.\n\nZoom link: https://utoronto.zoom.us/j/84117185836\n
LOCATION:https://stable.researchseminars.org/talk/UofT_GandT/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Freid Tong (Columbia University)
DTSTART:20201109T210000Z
DTEND:20201109T220000Z
DTSTAMP:20260404T095827Z
UID:UofT_GandT/7
DESCRIPTION:Title: <a href="https://stable.researchseminars.org/talk/UofT_
 GandT/7/">Asymptotically conical Calabi-Yau metrics with singularities</a>
 \nby Freid Tong (Columbia University) as part of University of Toronto Geo
 metry & Topology seminar\n\n\nAbstract\nAsymptotically conical Calabi-Yau 
 manifolds are a special class of complete Ricci-flat Kähler manifold that
  are asymptotic to a cone at infinity. Their importance lies in the fact t
 hat they often appear as blow-up models for degenerations of non-collapsed
  Kahler-Einstein metrics near a singular limit. The first general construc
 tion of asymptotically conical Calabi-Yau manifolds using analytic techniq
 ues goes back to the work of Tian-Yau in the 90s\, and the analytic theory
  was subsequently refined and is now very well developed. In this talk\, I
  will first review the theory of asymptotically conical Calabi-Yau metrics
 \, then I will discuss some work on the study of degenerations of asymptot
 ically conical Calabi-Yau metrics and applications to constructing asympto
 tically conical Calabi-Yau metrics with singularities. This is joint work 
 with Tristan Collins and Bin Guo.\n\nThe talk will be on Zoom at https://u
 toronto.zoom.us/j/81789338490 Passcode: 257573\n
LOCATION:https://stable.researchseminars.org/talk/UofT_GandT/7/
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