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BEGIN:VEVENT
SUMMARY:Otis Chodosh (Stanford)
DTSTART;VALUE=DATE-TIME:20201020T134500Z
DTEND;VALUE=DATE-TIME:20201020T144500Z
DTSTAMP;VALUE=DATE-TIME:20210612T224439Z
UID:BOWL/1
DESCRIPTION:Title: Gen
eric regularity of min-max minimal hypersurfaces in eight dimensions\n
by Otis Chodosh (Stanford) as part of B.O.W.L Geometry Seminar\n\nAbstract
: TBA\n
LOCATION:https://researchseminars.org/talk/BOWL/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Colleen Robles (Duke)
DTSTART;VALUE=DATE-TIME:20201027T134500Z
DTEND;VALUE=DATE-TIME:20201027T144500Z
DTSTAMP;VALUE=DATE-TIME:20210612T224439Z
UID:BOWL/2
DESCRIPTION:Title: Com
pletions of period mappings\nby Colleen Robles (Duke) as part of B.O.W
.L Geometry Seminar\n\n\nAbstract\nIt’s a long standing problem in Hodge
theory to complete the image of a period map. The latter arise in the st
udy of algebraic moduli\, and are proper holomorphic maps into locally hom
ogeneous spaces that are subject to a differential constraint. I’ll giv
e a survey of the problem and then describe recent progress\, with an emph
asis on the role of complex geometry and Lie theory. Joint with Mark Gree
n and Phillip Griffiths.\n
LOCATION:https://researchseminars.org/talk/BOWL/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Marco Guaraco (Imperial)
DTSTART;VALUE=DATE-TIME:20201103T134500Z
DTEND;VALUE=DATE-TIME:20201103T144500Z
DTSTAMP;VALUE=DATE-TIME:20210612T224439Z
UID:BOWL/3
DESCRIPTION:Title: Mul
tiplicity one of generic stable Allen-Cahn minimal hypersurfaces\nby M
arco Guaraco (Imperial) as part of B.O.W.L Geometry Seminar\n\n\nAbstract\
nAllen-Cahn (AC) minimal hypersurfaces are limits of nodal sets of solutio
ns to the AC equation. An important problem is to understand the local pic
ture of this convergence. For instance\, can we avoid the situation in whi
ch the nodal set looks like a multigraph over the limit hypersurface? Gene
ral examples of this phenomenon\, known as “multiplicity” or "interfac
e foliation”\, exist when the limit hypersurface is unstable. Together
with A. Neves and F. Marques we proved that\, generically and in all dimen
sions\, these are the only possible examples of interface foliation\, i.e.
generic stable AC minimal hypersurfaces can only occur with multiplicity
one. We will discuss this and other topics.\n
LOCATION:https://researchseminars.org/talk/BOWL/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tristan Ozuch-Meersseman (MIT)
DTSTART;VALUE=DATE-TIME:20201110T134500Z
DTEND;VALUE=DATE-TIME:20201110T144500Z
DTSTAMP;VALUE=DATE-TIME:20210612T224439Z
UID:BOWL/4
DESCRIPTION:Title: Hig
her order obstructions to the desingularization of Einstein metrics\nb
y Tristan Ozuch-Meersseman (MIT) as part of B.O.W.L Geometry Seminar\n\n\n
Abstract\nWe exhibit new obstructions to the desingularization of Einstein
metrics in dimension 4. These obstructions are specific to the compact si
tuation and raise the question of whether or not a sequence of Einstein me
trics degenerating while bubbling out gravitational instantons has to be K
ähler-Einstein. We then test these obstructions to discuss the possibilit
y of producing a Ricci-flat but not Kähler metric by the promising desing
ularization configuration proposed by Page in 1981.\n
LOCATION:https://researchseminars.org/talk/BOWL/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jean-Pierre Demailly (Institut Fourier)
DTSTART;VALUE=DATE-TIME:20201117T134500Z
DTEND;VALUE=DATE-TIME:20201117T144500Z
DTSTAMP;VALUE=DATE-TIME:20210612T224439Z
UID:BOWL/5
DESCRIPTION:Title: Her
mitian-Yang-Mills approach to the conjecture of Griffiths on the positivit
y of ample vector bundles\nby Jean-Pierre Demailly (Institut Fourier)
as part of B.O.W.L Geometry Seminar\n\n\nAbstract\nGiven a vector bundle o
f arbitrary rank with ample determinant line\nbundle on a projective manif
old\, we propose a new elliptic system of\ndifferential equations of Hermi
tian-Yang-Mills type for the curvature\ntensor. The system is designed so
that solutions provide Hermitian\nmetrics with positive curvature in the
sense of Griffiths – and even\nin the dual Nakano sense. As a consequenc
e\, if an existence result\ncould be obtained for every ample vector bundl
e\, the Griffiths\nconjecture on the equivalence between ampleness and pos
itivity of\nvector bundles would be settled. Another outcome of the approa
ch is a\nnew concept of volume for vector bundles.\n
LOCATION:https://researchseminars.org/talk/BOWL/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dario Beraldo (University College London)
DTSTART;VALUE=DATE-TIME:20201124T134500Z
DTEND;VALUE=DATE-TIME:20201124T144500Z
DTSTAMP;VALUE=DATE-TIME:20210612T224439Z
UID:BOWL/6
DESCRIPTION:Title: On
the geometry of Bun_G near infinity\nby Dario Beraldo (University Coll
ege London) as part of B.O.W.L Geometry Seminar\n\n\nAbstract\nLet Bun_G b
e the moduli stack of G-bundles on a compact Riemann surface. After review
ing (and motivating) the notion of "temperedness" appearing in the geometr
ic Langlands program\, I will discuss the proof of a conjecture of Gaitsgo
ry stating that the constant D-module on Bun_G is anti-tempered. No prior
familiarity with geometric Langlands will be assumed\; rather\, I'll empha
size some key ingredients that might be of broader interest: a Serre duali
ty in an unusual context and various cohomology vanishing computations.\n
LOCATION:https://researchseminars.org/talk/BOWL/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jasmin Hörter (Karlsruhe)
DTSTART;VALUE=DATE-TIME:20201201T134500Z
DTEND;VALUE=DATE-TIME:20201201T144500Z
DTSTAMP;VALUE=DATE-TIME:20210612T224439Z
UID:BOWL/7
DESCRIPTION:Title: Lim
its of epsilon-harmonic maps\nby Jasmin Hörter (Karlsruhe) as part of
B.O.W.L Geometry Seminar\n\n\nAbstract\nIn 1981 Sacks and Uhlenbeck intro
duced their famous alpha-approximation of the Dirichlet energy for maps fr
om surfaces and showed that critical points converge to a harmonic map (aw
ay from finitely many points). Now one can ask whether every harmonic map
is captured by this limiting process. Lamm\, Malchiodi and Micallef answer
ed this for maps from the two sphere into the two sphere and showed that t
he Sacks-Uhlenbeck method produces only constant maps and rotations if the
energy lies below a certain threshold. We investigate the same question f
or the epsilon-approximation of the Dirichlet energy.\nJoint work with Tob
ias Lamm and Mario Micallef.\n
LOCATION:https://researchseminars.org/talk/BOWL/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nikon Kurnosov (University College London)
DTSTART;VALUE=DATE-TIME:20201208T134500Z
DTEND;VALUE=DATE-TIME:20201208T144500Z
DTSTAMP;VALUE=DATE-TIME:20210612T224439Z
UID:BOWL/8
DESCRIPTION:Title: Def
ormation theory and geometry of Bogomolov-Guan manifolds\nby Nikon Kur
nosov (University College London) as part of B.O.W.L Geometry Seminar\n\n\
nAbstract\nIn 1994\, Guan published a series of papers constructing non-K
ähler holomorphic symplectic manifolds\, challenging a conjecture by Todo
rov. These examples\, called now BG manifolds were given a more transparen
t presentation by Bogomolov in 96 which emphasizes the analogy with Kodair
a-Thurston example of non-Kähler symplectic surfaces. We will discuss som
e important properties of BG manifolds: the deformation theory which is qu
ite similar to that of hyperkahler case\, algebraic reduction and submanif
olds.\n
LOCATION:https://researchseminars.org/talk/BOWL/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Casey Kelleher (Princeton)
DTSTART;VALUE=DATE-TIME:20201215T134500Z
DTEND;VALUE=DATE-TIME:20201215T144500Z
DTSTAMP;VALUE=DATE-TIME:20210612T224439Z
UID:BOWL/9
DESCRIPTION:Title: Gap
Theorem Results in Yang--Mills Theory\nby Casey Kelleher (Princeton)
as part of B.O.W.L Geometry Seminar\n\n\nAbstract\nWe discuss results conc
erning the space of Yang--Mills connections on vector bundles over compact
4-dimensional Riemannian manifolds. In particular\, we discuss a conforma
lly invariant gap theorem for Yang-Mills connections obtained by exploitin
g an associated Yamabe-type problem. We also discuss a bound for the index
in terms of its energy which is conformally invariant\, which captures th
e sharp growth rate. This is joint work with M. Gursky and J. Streets.\n
LOCATION:https://researchseminars.org/talk/BOWL/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Fritz Hiesmayr (UCL)
DTSTART;VALUE=DATE-TIME:20210119T134500Z
DTEND;VALUE=DATE-TIME:20210119T144500Z
DTSTAMP;VALUE=DATE-TIME:20210612T224439Z
UID:BOWL/10
DESCRIPTION:Title: A
Bernstein-type theorem for two-valued minimal graphs in dimension four
\nby Fritz Hiesmayr (UCL) as part of B.O.W.L Geometry Seminar\n\n\nAbstrac
t\nThe Bernstein theorem is a classical result for minimal graphs. It stat
es that\na globally defined solution of the minimal surface equation on $\
\mathbb{R}^n$ must be linear\,\nprovided the dimension is small enough. We
present an analogous theorem for\ntwo-valued minimal graphs\, valid in di
mension four. By definition two-valued\nfunctions take values in the unord
ered pairs of real numbers\; they arise as the\nlocal model of branch poin
t singularities. The plan is to juxtapose this with the\nclassical single-
valued theory\, and explain where some of the difficulties emerge\nin the
two-valued setting.\n
LOCATION:https://researchseminars.org/talk/BOWL/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Theodora Bourni (Tennessee)
DTSTART;VALUE=DATE-TIME:20210126T134500Z
DTEND;VALUE=DATE-TIME:20210126T144500Z
DTSTAMP;VALUE=DATE-TIME:20210612T224439Z
UID:BOWL/11
DESCRIPTION:Title: An
cient solutions to mean curvature flow\nby Theodora Bourni (Tennessee)
as part of B.O.W.L Geometry Seminar\n\n\nAbstract\nMean curvature flow (M
CF) is the gradient flow of the area functional\; it moves the surface in
the direction of steepest decrease of area. An important motivation for t
he study of MCF comes from its potential geometric applications\, such as
classification theorems and geometric inequalities. MCF develops “singul
arities” (curvature blow-up)\, which obstruct the flow from existing for
all times and therefore understanding these high curvature regions is of
great interest. This is done by studying ancient solutions\, solutions th
at have existed for all times in the past\, and which model singularities.
In this talk we will discuss their importance and ways of constructing an
d classifying such solutions. In particular\, we will focus on “collapse
d” solutions and construct\, in all dimensions $n\\geq 2$\, a large fami
ly of new examples\, including both symmetric and asymmetric examples\, as
well as many eternal examples that do not evolve by translation. Moreover
\, we will show that collapsed solutions decompose “backwards in time
” into a canonical configuration of Grim hyperplanes which satisfies cer
tain necessary conditions. This is joint work with Mat Langford and Giusep
pe Tinaglia.\n
LOCATION:https://researchseminars.org/talk/BOWL/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Chao Li (Princeton)
DTSTART;VALUE=DATE-TIME:20210202T134500Z
DTEND;VALUE=DATE-TIME:20210202T144500Z
DTSTAMP;VALUE=DATE-TIME:20210612T224439Z
UID:BOWL/12
DESCRIPTION:Title: Sc
alar curvature on aspherical manifolds\nby Chao Li (Princeton) as part
of B.O.W.L Geometry Seminar\n\n\nAbstract\nIt has been a classical questi
on which manifolds admit Riemannian metrics with positive scalar curvature
. I will first review some history of this question\, and present some rec
ent progress\, ruling out positive scalar curvature on closed aspherical m
anifolds of dimensions 4 and 5 (as conjectured by Schoen-Yau and by Gromov
). I will also discuss some related questions including the Urysohn width
inequalities on manifolds with scalar curvature lower bounds. This talk is
based on joint work with Otis Chodosh.\n
LOCATION:https://researchseminars.org/talk/BOWL/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Claude LeBrun (Stony Brook)
DTSTART;VALUE=DATE-TIME:20210216T134500Z
DTEND;VALUE=DATE-TIME:20210216T144500Z
DTSTAMP;VALUE=DATE-TIME:20210612T224439Z
UID:BOWL/14
DESCRIPTION:Title: An
ti-self-dual 4-manifolds\, quasi-Fuchsian groups\, and almost Kähler geom
etry\nby Claude LeBrun (Stony Brook) as part of B.O.W.L Geometry Semin
ar\n\n\nAbstract\nIt is known that the almost-Kähler anti-self-dual metri
cs on a given 4-manifold sweep out an open subset in the moduli space of a
nti-self-dual metrics. However\, we show by example that this subset is no
t generally closed\, and does not always sweep out entire connected compon
ents in the moduli space. The construction hinges on an unexpected link be
tween harmonic functions on certain hyperbolic 3-manifolds and self-dual h
armonic 2-forms on associated 4-manifolds.\n
LOCATION:https://researchseminars.org/talk/BOWL/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Eleonora Di Nezza (École Polytechnique)
DTSTART;VALUE=DATE-TIME:20210223T134500Z
DTEND;VALUE=DATE-TIME:20210223T144500Z
DTSTAMP;VALUE=DATE-TIME:20210612T224439Z
UID:BOWL/15
DESCRIPTION:Title: Fa
milies of Kähler-Einstein metrics\nby Eleonora Di Nezza (École Polyt
echnique) as part of B.O.W.L Geometry Seminar\n\n\nAbstract\nIn a lot of g
eometric situation we need to work with families of varieties. In this tal
k we focus on families of singular Kähler-Einstein metric. In particular
we study the case of a family of Kähler varieties and we develop the firs
t steps of pluripotential theory in family\, which will allow us to have a
control on the $C^0$ estimate when the complex structure varies. This typ
e of result will be applied in different geometric contexts. This is a joi
nt work with V. Guedj and H. Guenancia.\n
LOCATION:https://researchseminars.org/talk/BOWL/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gábor Székelyhidi (Notre Dame)
DTSTART;VALUE=DATE-TIME:20210302T134500Z
DTEND;VALUE=DATE-TIME:20210302T144500Z
DTSTAMP;VALUE=DATE-TIME:20210612T224439Z
UID:BOWL/16
DESCRIPTION:Title: Un
iqueness of certain cylindrical tangent cones\nby Gábor Székelyhidi
(Notre Dame) as part of B.O.W.L Geometry Seminar\n\n\nAbstract\nLeon Simon
showed that if an area minimizing hypersurface admits a cylindrical tange
nt cone of the form $C \\times \\mathbb{R}$\, then this tangent cone is un
ique for a large class of minimal cones $C$. One of the hypotheses in this
result is that $C \\times \\mathbb{R}$ is integrable and this excludes th
e case when $C$ is the Simons cone over $S^3\\times S^3$. The main result
in this talk is that the uniqueness of the tangent cone holds in this case
too. The new difficulty in this non-integrable situation is to develop a
version of the Lojasiewicz-Simon inequality that can be used in the settin
g of tangent cones with non-isolated singularities.\n
LOCATION:https://researchseminars.org/talk/BOWL/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Richard Bamler (Berkeley)
DTSTART;VALUE=DATE-TIME:20210309T170000Z
DTEND;VALUE=DATE-TIME:20210309T180000Z
DTSTAMP;VALUE=DATE-TIME:20210612T224439Z
UID:BOWL/17
DESCRIPTION:Title: Co
mpactness and partial regularity theory of Ricci flows in higher dimension
s\nby Richard Bamler (Berkeley) as part of B.O.W.L Geometry Seminar\n\
n\nAbstract\nWe present a new compactness theory of Ricci flows. This theo
ry states that any sequence of Ricci flows that is pointed in an appropria
te sense\, subsequentially converges to a synthetic flow. Under a natural
non-collapsing condition\, this limiting flow is smooth on the complement
of a singular set of parabolic codimension at least 4. We furthermore obta
in a stratification of the singular set with optimal dimensional bounds de
pending on the symmetries of the tangent flows. Our methods also imply the
corresponding quantitative stratification result and the expected $L^p$-
curvature bounds.\n\nAs an application we obtain a description of the sing
ularity formation at the first singular time and a long-time characterizat
ion of immortal flows\, which generalizes the thick-thin decomposition in
dimension 3. We also obtain a backwards pseudolocality theorem and discuss
several other applications.\n
LOCATION:https://researchseminars.org/talk/BOWL/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Robin Neumayer (Northwestern)
DTSTART;VALUE=DATE-TIME:20210316T134500Z
DTEND;VALUE=DATE-TIME:20210316T144500Z
DTSTAMP;VALUE=DATE-TIME:20210612T224439Z
UID:BOWL/18
DESCRIPTION:Title: $d
_p$ Convergence and $\\varepsilon$-regularity theorems for entropy and sca
lar curvature lower bounds\nby Robin Neumayer (Northwestern) as part o
f B.O.W.L Geometry Seminar\n\n\nAbstract\nIn this talk\, we consider Riema
nnian manifolds with almost non-negative scalar curvature and Perelman ent
ropy. We establish an $\\varepsilon$-regularity theorem showing that such
a space must be close to Euclidean space in a suitable sense. Interestingl
y\, such a result is false with respect to the Gromov-Hausdorff and Intrin
sic Flat distances\, and more generally the metric space structure is not
controlled under entropy and scalar lower bounds. Instead\, we introduce t
he notion of the $d_p$ distance between (in particular) Riemannian manifol
ds\, which measures the distance between $W^{1\,p}$ Sobolev spaces\, and i
t is with respect to this distance that the epsilon regularity theorem hol
ds. We will discuss various applications to manifolds with scalar curvatur
e and entropy lower bounds\, including a compactness and limit structure t
heorem for sequences\, a uniform $L^\\infty$ Sobolev embedding\, and a pri
ori $L^p$ scalar curvature bounds for $p<1$. This is joint work with Man-C
hun Lee and Aaron Naber.\n
LOCATION:https://researchseminars.org/talk/BOWL/18/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yi Lai (Berkeley)
DTSTART;VALUE=DATE-TIME:20210323T134500Z
DTEND;VALUE=DATE-TIME:20210323T144500Z
DTSTAMP;VALUE=DATE-TIME:20210612T224439Z
UID:BOWL/19
DESCRIPTION:Title: A
family of 3d steady gradient solitons that are flying wings\nby Yi Lai
(Berkeley) as part of B.O.W.L Geometry Seminar\n\n\nAbstract\nWe find a f
amily of 3d steady gradient Ricci solitons that are flying wings. This ver
ifies a conjecture by Hamilton. For a 3d flying wing\, we show that the sc
alar curvature does not vanish at infinity. The 3d flying wings are collap
sed. For dimension $n \\geq 4$\, we find a family of $\\mathbb{Z}_2 \\time
s O(n − 1)$-symmetric but non-rotationally symmetric n-dimensional stead
y gradient solitons with positive curvature operator. We show that these s
olitons are non-collapsed.\n
LOCATION:https://researchseminars.org/talk/BOWL/19/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ilaria Mondello (Paris-Est Créteil)
DTSTART;VALUE=DATE-TIME:20210330T124500Z
DTEND;VALUE=DATE-TIME:20210330T134500Z
DTSTAMP;VALUE=DATE-TIME:20210612T224439Z
UID:BOWL/20
DESCRIPTION:Title: Li
mits of manifolds with a Kato bound on the Ricci curvature\nby Ilaria
Mondello (Paris-Est Créteil) as part of B.O.W.L Geometry Seminar\n\n\nAbs
tract\nStarting from Gromov pre-compactness theorem\, a vast theory about
the structure of limits of manifolds with a lower bound on the Ricci curva
ture has been developed thanks to the work of J. Cheeger\, T.H. Colding\,
M. Anderson\, G. Tian\, A. Naber\, W. Jiang. Nevertheless\, in some situat
ions\, for instance in the study of geometric flows\, there is no lower bo
und on the Ricci curvature. It is then important to understand what happen
s when having a weaker condition. \n\nIn this talk\, we present new result
s about limits of manifolds with a Kato bound on the negative part of the
Ricci tensor. Such bound is weaker than the previous $L^p$ bounds consider
ed in the literature (P. Petesern\, G. Wei\, G. Tian\, Z. Zhang\, C. Rose\
, L. Chen\, C. Ketterer…). In the non-collapsing case\, we recover part
of the regularity theory that was known in the setting of Ricci lower boun
ds: in particular\, we obtain that all tangent cones are metric cones\, a
stratification result and volume convergence to the Hausdorff measure. Aft
er presenting the setting and main theorem\, we will focus on proving that
tangent cones are metric cones\, and in particular on the study of the ap
propriate monotone quantities that leads to this result.\n
LOCATION:https://researchseminars.org/talk/BOWL/20/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Rober Haslhofer (Toronto)
DTSTART;VALUE=DATE-TIME:20210504T124500Z
DTEND;VALUE=DATE-TIME:20210504T134500Z
DTSTAMP;VALUE=DATE-TIME:20210612T224439Z
UID:BOWL/21
DESCRIPTION:Title: Me
an curvature flow through neck-singularities\nby Rober Haslhofer (Toro
nto) as part of B.O.W.L Geometry Seminar\n\n\nAbstract\nIn this talk\, I w
ill explain our recent work showing that mean curvature flow through neck-
singularities is unique. The key is a classification result for ancient as
ymptotically cylindrical flows that describes all possible blowup limits n
ear a neck-singularity. In particular\, this confirms Ilmanen’s mean-con
vex neighborhood conjecture\, and more precisely gives a canonical neighbo
rhood theorem for neck-singularities. Furthermore\, assuming the multiplic
ity-one conjecture\, we conclude that for embedded two-spheres mean curvat
ure flow through singularities is well-posed. The two-dimensional case is
joint work with Choi and Hershkovits\, and the higher-dimensional case is
joint with Choi\, Hershkovits and White.\n
LOCATION:https://researchseminars.org/talk/BOWL/21/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gilles Carron (Nantes)
DTSTART;VALUE=DATE-TIME:20210511T124500Z
DTEND;VALUE=DATE-TIME:20210511T134500Z
DTSTAMP;VALUE=DATE-TIME:20210612T224439Z
UID:BOWL/22
DESCRIPTION:Title: Ri
gidity of the Euclidean heat kernel\nby Gilles Carron (Nantes) as part
of B.O.W.L Geometry Seminar\n\n\nAbstract\nIt is a joint work with David
Tewodrose (Bruxelles) https://arxiv.org/abs/1912.10759. I will explain tha
t a metric measure space with Euclidean heat kernel is Euclidean. An almo
st rigidity result comes then for free\, and this can be used to give ano
ther proof of Colding’s almost rigidity for complete manifold with non n
egative Ricci curvature and almost Euclidean growth.\n
LOCATION:https://researchseminars.org/talk/BOWL/22/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yevgeny Liokumovich (Toronto)
DTSTART;VALUE=DATE-TIME:20210518T124500Z
DTEND;VALUE=DATE-TIME:20210518T134500Z
DTSTAMP;VALUE=DATE-TIME:20210612T224439Z
UID:BOWL/23
DESCRIPTION:Title: Fo
liations of 3-manifolds of positive scalar curvature by surfaces of contro
lled size\nby Yevgeny Liokumovich (Toronto) as part of B.O.W.L Geometr
y Seminar\n\n\nAbstract\nLet M be a compact 3-manifold with scalar curvatu
re at least 1. We show that there exists a Morse function f on M\, such th
at every connected component of every fiber of f has genus\, area and diam
eter bounded by a universal constant. The proof uses Min-Max theory and Me
an Curvature Flow. This is a joint work with Davi Maximo. Time permitting\
, I will discuss a related problem for macroscopic scalar curvature in met
ric spaces (joint with Boris Lishak\, Alexander Nabutovsky and Regina Rotm
an).\n
LOCATION:https://researchseminars.org/talk/BOWL/23/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Costante Bellettini (UCL)
DTSTART;VALUE=DATE-TIME:20210525T124500Z
DTEND;VALUE=DATE-TIME:20210525T134500Z
DTSTAMP;VALUE=DATE-TIME:20210612T224439Z
UID:BOWL/24
DESCRIPTION:Title: Ex
istence of hypersurfaces with prescribed mean-curvature\nby Costante B
ellettini (UCL) as part of B.O.W.L Geometry Seminar\n\n\nAbstract\nLet N b
e a compact Riemannian manifold of dimension 3 or higher\, and g a Lipschi
tz non-negative (or non-positive) function on N. We prove that there exist
s a closed hypersurface M whose mean curvature attains the values prescrib
ed by g (joint work with Neshan Wickramasekera\, Cambridge). Except possib
ly for a small singular set (of codimension 7 or higher)\, the hypersurfac
e M is C^2 immersed and two-sided (it admits a global unit normal)\; the s
calar mean curvature at x is g(x) with respect to a global choice of unit
normal. More precisely\, the immersion is a quasi-embedding\, namely the o
nly non-embedded points are caused by tangential self-intersections: aroun
d such a non-embedded point\, the local structure is given by two disks\,
lying on one side of each other\, and intersecting tangentially (as in the
case of two spherical caps touching at a point). A special case of PMC (p
rescribed-mean-curvature) hypersurfaces is obtained when g is a constant\,
in which the above result gives a CMC (constant-mean-curvature) hypersurf
ace for any prescribed value of the mean curvature. The construction of M
is carried out largely by means of PDE principles: (i) a minmax for an All
en–Cahn (or Modica-Mortola) energy\, involving a parameter that\, when s
ent to 0\, leads to an interface from which the desired PMC hypersurface i
s extracted\; (ii) quasi-linear elliptic PDE and geometric-measure-theory
arguments\, to obtain regularity conclusions for said interface\; (iii) pa
rabolic semi-linear PDE (together with specific features of the Allen-Cahn
framework)\, to tackle cancellation phenomena that can happen when sendin
g to 0 the Allen-Cahn parameter.\n
LOCATION:https://researchseminars.org/talk/BOWL/24/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hans-Joachim Hein (Münster)
DTSTART;VALUE=DATE-TIME:20210601T124500Z
DTEND;VALUE=DATE-TIME:20210601T134500Z
DTSTAMP;VALUE=DATE-TIME:20210612T224439Z
UID:BOWL/25
DESCRIPTION:Title: Sm
ooth asymptotics for collapsing Calabi-Yau metrics\nby Hans-Joachim He
in (Münster) as part of B.O.W.L Geometry Seminar\n\n\nAbstract\nI will pr
esent recent joint work with Valentino Tosatti in which we obtain a comple
te asymptotic expansion (locally uniformly away from the singular fibers)
of Calabi-Yau metrics collapsing along a holomorphic fibration of a fixed
compact Calabi-Yau manifold. The result is weaker than a standard asymptot
ic expansion in that the coefficient functions might still depend on the s
mall parameter in some unknown way in the base variables. However\, it is
far stronger in that all terms including the remainder at each order are p
roved to be uniformly bounded in C^k for all k. We also calculate the firs
t nontrivial coefficient in terms of the Kodaira-Spencer forms of the fibr
ation.\n
LOCATION:https://researchseminars.org/talk/BOWL/25/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Anna Siffert (Münster)
DTSTART;VALUE=DATE-TIME:20210608T124500Z
DTEND;VALUE=DATE-TIME:20210608T134500Z
DTSTAMP;VALUE=DATE-TIME:20210612T224439Z
UID:BOWL/26
DESCRIPTION:Title: Co
nstruction of explicit p-harmonic functions\nby Anna Siffert (Münster
) as part of B.O.W.L Geometry Seminar\n\n\nAbstract\nThe study of p-harmon
ic functions on Riemannian manifolds has invoked the interest of mathemati
cians and physicists for nearly two centuries. Applications within physics
can for example be found in continuum mechanics\, elasticity theory\, as
well as two-dimensional hydrodynamics problems involving Stokes flows of i
ncompressible Newtonian fluids. In my talk I will focus on the constructio
n of explicit p-harmonic functions on rank-one Lie groups of Iwasawa type.
This joint wok with Sigmundur Gudmundsson and Marko Sobak.\n
LOCATION:https://researchseminars.org/talk/BOWL/26/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Laura Fredrickson (Oregon)
DTSTART;VALUE=DATE-TIME:20210615T150000Z
DTEND;VALUE=DATE-TIME:20210615T160000Z
DTSTAMP;VALUE=DATE-TIME:20210612T224439Z
UID:BOWL/27
DESCRIPTION:Title: AL
G Gravitational Instantons and Hitchin Moduli Spaces\nby Laura Fredric
kson (Oregon) as part of B.O.W.L Geometry Seminar\n\n\nAbstract\nFour-dime
nsional complete hyperkaehler manifolds can be classified into ALE\, ALF\,
ALG\, ALG*\, ALH\, ALH* families. It has been conjectured that every ALG
or ALG* hyperkaehler metric can be realized as a 4d Hitchin moduli space.
I will describe ongoing work with Rafe Mazzeo\, Jan Swoboda\, and Hartmu
t Weiss to prove a special case of the conjecture\, and some consequences.
The hyperkaehler metrics on Hitchin moduli spaces are of independent int
erest\, as the physicists Gaiotto—Moore—Neitzke give an intricate conj
ectural description of their asymptotic geometry.\n
LOCATION:https://researchseminars.org/talk/BOWL/27/
END:VEVENT
END:VCALENDAR