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BEGIN:VEVENT
SUMMARY:Ruochuan Liu (Peking University)
DTSTART;VALUE=DATE-TIME:20201023T101500Z
DTEND;VALUE=DATE-TIME:20201023T111500Z
DTSTAMP;VALUE=DATE-TIME:20240423T105100Z
UID:BeijingMoscowColloquium/1
DESCRIPTION:Title: Topological cyclic homology for p-adic local fields\nb
y Ruochuan Liu (Peking University) as part of Beijing Moscow Mathematics C
olloquium\n\n\nAbstract\nWe introduce a new approach to compute topologica
l cyclic homology using the descent spectral sequence and the algebraic Ta
te spectral sequence. We carry out computations in the case of a $p$-adic
local field with coefficient ${\\mathbb F}_p$. Joint work with Guozhen Wan
g.\n\nMeeting ID: 648 6454 8936 Password: 899678\n
LOCATION:https://researchseminars.org/talk/BeijingMoscowColloquium/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dmitry Frolenkov (Steklov Mathematical Institute of RAS)
DTSTART;VALUE=DATE-TIME:20201023T111500Z
DTEND;VALUE=DATE-TIME:20201023T121500Z
DTSTAMP;VALUE=DATE-TIME:20240423T105100Z
UID:BeijingMoscowColloquium/2
DESCRIPTION:Title: Additive divisor problem and Applications\nby Dmitry F
rolenkov (Steklov Mathematical Institute of RAS) as part of Beijing Moscow
Mathematics Colloquium\n\n\nAbstract\nAdditive Divisor Problem (ADP) is c
oncerned with finding an asymptotic formula for the sum $\\sum_{n< X}d(n)d
(n+a)$\, where $d(n)=\\sum_{d|n}1$ is the divisor function. Surprisingly\,
the ADP arises naturally in quite different problems of number theory. Fo
r example\, it is related to the investigation of the 4th moment of the Ri
emann zeta-function\, the second moment of automorphic L-functions and the
mean values of the length of continued fractions. In the talk\, I will de
scribe the ADP and its applications.\n\nMeeting ID：648 6454 8936 Passwor
d：899678\n
LOCATION:https://researchseminars.org/talk/BeijingMoscowColloquium/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yi Shi (Peking University)
DTSTART;VALUE=DATE-TIME:20201106T080000Z
DTEND;VALUE=DATE-TIME:20201106T090000Z
DTSTAMP;VALUE=DATE-TIME:20240423T105100Z
UID:BeijingMoscowColloquium/3
DESCRIPTION:Title: Spectrum rigidity and integrability for Anosov diffeomorph
isms\nby Yi Shi (Peking University) as part of Beijing Moscow Mathemat
ics Colloquium\n\n\nAbstract\nLet $f$ be a partially hyperbolic derived-fr
om-Anosov diffeomorphism on 3-torus $\\mathbb{T}^3$. We show that the stab
le and unstable bundle of $f$ is jointly integrable if and only if $f$ is
Anosov and admits spectrum rigidity in the center bundle. This proves the
Ergodic Conjecture on $\\mathbb{T}^3$.\n\nIn higher dimensions\, let $A\\i
n{\\rm SL}(n\,\\mathbb{Z})$ be an irreducible hyperbolic matrix admitting
complex simple spectrum with different moduli\, then $A$ induces a diffeom
orphism on $\\mathbb{T}^n$. We will also discuss the equivalence of integr
ability and spectrum rigidity for $f\\in{\\rm Diff}^2(\\mathbb{T}^n)$ whic
h is $C^1$-close to $A$.\n\nZoom Meeting ID: 674 4141 7410\nPassword: 9051
98\n
LOCATION:https://researchseminars.org/talk/BeijingMoscowColloquium/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lev Lokutsievskiy (Steklov Mathematical Institute of RAS)
DTSTART;VALUE=DATE-TIME:20201106T090000Z
DTEND;VALUE=DATE-TIME:20201106T100000Z
DTSTAMP;VALUE=DATE-TIME:20240423T105100Z
UID:BeijingMoscowColloquium/4
DESCRIPTION:Title: Аn application of algebraic topology and graph theory in
microeconomics\nby Lev Lokutsievskiy (Steklov Mathematical Institute o
f RAS) as part of Beijing Moscow Mathematics Colloquium\n\n\nAbstract\nOne
of the important questions in mechanism design is the implementability of
allocation rules. An allocation rule is called implementable if for any a
gent\, benefit from revealing its true type is better than benefit from ly
ing. I’ll show some illustrative examples. Obviously\, some allocation r
ules are not implementable. Rochet’s theorem states that an allocation r
ule is implementable iff it is cyclically monotone. During the talk\, I’
ll present a new convenient topological condition that guarantees that cyc
lic monotonicity is equivalent to ordinary monotonicity. The last one is e
asy to check (in contrary to cyclic one). Graph theory and algebraic topol
ogy appear to be very useful here.\n\nZoom Meeting ID: 674 4141 7410 \nPas
sword: 905198\n
LOCATION:https://researchseminars.org/talk/BeijingMoscowColloquium/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Taras Panov (Moscow State University)
DTSTART;VALUE=DATE-TIME:20201120T080000Z
DTEND;VALUE=DATE-TIME:20201120T090000Z
DTSTAMP;VALUE=DATE-TIME:20240423T105100Z
UID:BeijingMoscowColloquium/5
DESCRIPTION:Title: Right-angled polytopes\, hyperbolic manifolds and torus ac
tions\nby Taras Panov (Moscow State University) as part of Beijing Mos
cow Mathematics Colloquium\n\n\nAbstract\nA combinatorial 3-dimensional po
lytope $P$ can be realized in Lobachevsky 3-space with right dihedral angl
es if and only if it is simple\, flag and does not have 4-belts of facets.
This criterion was proved in the works of A. Pogorelov and E. Andreev of
the 1960s. We refer to combinatorial 3 polytopes admitting a right-angled
realisation in Lobachevsky 3-space as Pogorelov polytopes. The Pogorelov c
lass contains all fullerenes\, i.e. simple 3-polytopes with only 5-gonal a
nd 6-gonal facets. There are two families of smooth manifolds associated w
ith Pogorelov polytopes. The first family consists of 3-dimensional small
covers (in the sense of M. Davis and T. Januszkiewicz) of Pogorelov polyto
pes $P$\, also known as hyperbolic 3-manifolds of Loebell type. These are
aspherical 3-manifolds whose fundamental groups are certain extensions of
abelian 2-groups by hyperbolic right-angled reflection groups in the facet
s of $P$. The second family consists of 6-dimensional quasi toric manifold
s over Pogorelov polytopes. These are simply connected 6-manifolds with a
3-dimensional torus action and orbit space $P$. Our main result is that bo
th families are cohomologically rigid\, i.e. two manifolds $M$ and $M'$ fr
om either family are diffeomorphic if and only if their cohomology rings a
re isomorphic. We also prove that a cohomology ring isomorphism implies an
equivalence of characteristic pairs\; in particular\, the corresponding p
olytopes $P$ and $P'$ are combinatorially equivalent. This leads to a posi
tive solution of a problem of A. Vesnin (1991) on hyperbolic Loebell manif
olds\, and implies their full classification. Our results are intertwined
with classical subjects of geometry and topology such as combinatorics of
3-polytopes\, the Four Colour Theorem\, aspherical manifolds\, a diffeomor
phism classification of 6-manifolds and invariance of Pontryagin classes.
The proofs use techniques of toric topology. This is a joint work with V.
Buchstaber\, N. Erokhovets\, M. Masuda and S. Park.\n\nZoom Meeting ID: 62
6 6992 6224 Password: 363601\n
LOCATION:https://researchseminars.org/talk/BeijingMoscowColloquium/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yi Liu (Beijing International Center for Mathematical Research)
DTSTART;VALUE=DATE-TIME:20201120T090000Z
DTEND;VALUE=DATE-TIME:20201120T100000Z
DTSTAMP;VALUE=DATE-TIME:20240423T105100Z
UID:BeijingMoscowColloquium/6
DESCRIPTION:Title: Finite covers of 3-manifolds\nby Yi Liu (Beijing Inter
national Center for Mathematical Research) as part of Beijing Moscow Mathe
matics Colloquium\n\n\nAbstract\nIn this talk\, I will discuss some develo
pments in 3-manifold topology of this century regarding finite covering sp
aces. These developments led to the resolution of Thurston's virtual Haken
conjecture and other related conjectures around 2012. Since then\, people
have been seeking for new applications of those techniques and their comb
ination with other branches of mathematics.\n\nZoom Meeting ID: 626 6992 6
224 Password: 363601\n
LOCATION:https://researchseminars.org/talk/BeijingMoscowColloquium/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alexander Gaifullin (Steklov Mathematical Institute of RAS)
DTSTART;VALUE=DATE-TIME:20201204T080000Z
DTEND;VALUE=DATE-TIME:20201204T090000Z
DTSTAMP;VALUE=DATE-TIME:20240423T105100Z
UID:BeijingMoscowColloquium/7
DESCRIPTION:Title: On homology of Torelli groups\nby Alexander Gaifullin
(Steklov Mathematical Institute of RAS) as part of Beijing Moscow Mathemat
ics Colloquium\n\n\nAbstract\nThe mapping class groups of oriented surface
s are important examples of groups whose properties are closely related to
geometry and topology of moduli spaces\, topology of 3-manifolds\, automo
rphisms of free groups. The mapping class group of a closed oriented surfa
ce contains two important subgroups\, the Torelli group\, which consists o
f all mapping classes that act trivially on the homology of the surface\,
and the Johnson kernel\, which is the subgroup generated by all Dehn twist
s about separating curves. The talk will be devoted to results on homology
of these two subgroups. Namely\, we will show that the $k$-dimensional ho
mology group of the genus g Torelli group is not finitely generated\, prov
ided that k is in range from $2g-3$ and $3g-5$ (the case $3g-5$ was previo
usly known by a result of Bestvina\, Bux\, and Margalit)\, and the $(2g-3)
$-dimensional homology group the genus g Johnson kernel is also not finite
ly generated. The proof is based on a detailed study of the spectral seque
nces associated with the actions of these groups on the complex of cycles
constructed by Bestvina\, Bux\, and Margalit.\n\nZoom Meeting ID: 668 8175
3105\nPassword: 348558\n
LOCATION:https://researchseminars.org/talk/BeijingMoscowColloquium/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Guozhen Wang (Shanghai Center for Mathematical Sciences\, Fudan Un
iversity)
DTSTART;VALUE=DATE-TIME:20201204T090000Z
DTEND;VALUE=DATE-TIME:20201204T100000Z
DTSTAMP;VALUE=DATE-TIME:20240423T105100Z
UID:BeijingMoscowColloquium/8
DESCRIPTION:Title: Stable homotopy groups of spheres\nby Guozhen Wang (Sh
anghai Center for Mathematical Sciences\, Fudan University) as part of Bei
jing Moscow Mathematics Colloquium\n\n\nAbstract\nWe will discuss the curr
ent state of knowledge of stable homotopy groups of spheres. We describe a
computational method using motivic homotopy theory\, viewed as a deformat
ion of classical homotopy theory. This yields a streamlined computation of
the first 61 stable homotopy groups and gives information about the stabl
e homotopy groups in dimensions 62 through 90. As an application\, we dete
rmine the groups of homotopy spheres that classify smooth structures on sp
heres through dimension 90\, except for dimension 4. The method relies mor
e heavily on machine computations than previous methods and is therefore l
ess prone to error. The main mathematical tool is the Adams spectral seque
nce.\n\nZoom Meeting ID: 668 8175 3105 Password: 348558\n
LOCATION:https://researchseminars.org/talk/BeijingMoscowColloquium/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Zhifei Zhang (School of Mathematical Sciences\, Peking University)
DTSTART;VALUE=DATE-TIME:20210115T080000Z
DTEND;VALUE=DATE-TIME:20210115T090000Z
DTSTAMP;VALUE=DATE-TIME:20240423T105100Z
UID:BeijingMoscowColloquium/9
DESCRIPTION:Title: Linear stability of pipe Poiseuille flow at high Reynolds
number regime\nby Zhifei Zhang (School of Mathematical Sciences\, Peki
ng University) as part of Beijing Moscow Mathematics Colloquium\n\n\nAbstr
act\nThe linear stability of pipe Poiseuille flow is a long standing probl
em since Reynolds experiment in 1883. Joint with Qi Chen and Dongyi Wei\,
we solve this problem at high Reynolds regime. We first introduce a new fo
rmulation for the linearized 3-D Navier-Stokes equations around this flow.
Then we establish the resolvent estimates of this new system under favora
ble artificial boundary conditions. Finally\, we solve the original system
by constructing a boundary layer corrector.\n\nMeeting ID：645 2363 5960
\nPassword：714716\n
LOCATION:https://researchseminars.org/talk/BeijingMoscowColloquium/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Vladimir E. Nazaikinskii (Ishlinsky Institute for Problems in Mech
anics RAS)
DTSTART;VALUE=DATE-TIME:20210115T090000Z
DTEND;VALUE=DATE-TIME:20210115T100000Z
DTSTAMP;VALUE=DATE-TIME:20240423T105100Z
UID:BeijingMoscowColloquium/10
DESCRIPTION:Title: Partial spectral flow and the Aharonov-Bohm effect in gra
phene\nby Vladimir E. Nazaikinskii (Ishlinsky Institute for Problems i
n Mechanics RAS) as part of Beijing Moscow Mathematics Colloquium\n\n\nAbs
tract\nWe study the Aharonov-Bohm effect in an open-ended tube made of a g
raphene sheet whose dimensions are much larger than the interatomic distan
ce in graphene. An external magnetic field vanishes on and in the vicinity
of the graphene sheet\, and its flux through the tube is adiabatically sw
itched on. It is shown that\, in the process\, the energy levels of the ti
ght-binding Hamiltonian of $\\pi$-electrons unavoidably cross the Fermi le
vel\, which results in the creation of electron-hole pairs. The number of
pairs is proven to be equal to the number of magnetic flux quanta of the e
xternal field. The proof is based on the new notion of partial spectral fl
ow\, which generalizes the ordinary spectral flow introduced by Atiyah\, P
atodi\, and Singer and already having well-known applications (such as the
Kopnin forces in superconductors and superfluids) in condensed matter phy
sics.\n\nMeeting ID：645 2363 5960\nPassword：714716\n
LOCATION:https://researchseminars.org/talk/BeijingMoscowColloquium/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Armen Sergeev (Steklov Mathematical Institute of RAS)
DTSTART;VALUE=DATE-TIME:20210312T080000Z
DTEND;VALUE=DATE-TIME:20210312T090000Z
DTSTAMP;VALUE=DATE-TIME:20240423T105100Z
UID:BeijingMoscowColloquium/11
DESCRIPTION:Title: Mathematical problems in the theory of topological insula
tors\nby Armen Sergeev (Steklov Mathematical Institute of RAS) as part
of Beijing Moscow Mathematics Colloquium\n\n\nAbstract\nThe talk is devot
ed to the theory of topological insulators - a new and actively developing
direction in solid state physics. To find a new topological object one ha
ve to look for the appropiate topological invariants and systems for which
these invariants are non-trivial. The topological insulators are characte
rized by having wide energy gap stable for small deformations. A nice exam
ple is given by the quantum Hall spin insulator. It is a two-dimensional i
nsulator invariant under the time reversal. It is characterized by the non
-trivial topological $\\mathbb Z_2$-invariant introduced by Kane and Mele.
\nIn our talk we consider the topological insulators invariant under time
reversal. In the first part we present the physical basics of their theory
while the second part deals with the mathematical aspects. These aspects
are closely related to K-theory and non-commutative geometry.\n\nZoom Meet
ing ID: 646 2331 6558\nPassword：574262\n
LOCATION:https://researchseminars.org/talk/BeijingMoscowColloquium/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Oleg German (Moscow State University)
DTSTART;VALUE=DATE-TIME:20210326T080000Z
DTEND;VALUE=DATE-TIME:20210326T090000Z
DTSTAMP;VALUE=DATE-TIME:20240423T105100Z
UID:BeijingMoscowColloquium/12
DESCRIPTION:Title: Transference principle in Diophantine approximation\n
by Oleg German (Moscow State University) as part of Beijing Moscow Mathema
tics Colloquium\n\n\nAbstract\nThe talk will be devoted to one of the fund
amental principles in Diophantine approximation called transference princi
ple. It reflects the relation of duality between certain problems. This pr
inciple is usually formulated in terms of Diophantine exponents - they gen
eralise to the multidimensional case the measure of irrationality of a rea
l number. We plan to give an account on the existing relations Diophantine
exponents satisfy and try to reveal the geometric nature of those relatio
ns. After having described some basic geometric constructions\, we shall l
ook from this perspective at the famous linear independence criterion that
belongs to Nesterenko. It appears that our approach provides an alternati
ve proof of this criterion\, which bases on rather simple geometric consid
erations.\n\nZoom Meeting ID: 673 7981 0561\nPassword：263867\n
LOCATION:https://researchseminars.org/talk/BeijingMoscowColloquium/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hu Yongquan (Morningside Center of Mathematics\, Academy of Mathem
atics and Systems Science)
DTSTART;VALUE=DATE-TIME:20210326T090000Z
DTEND;VALUE=DATE-TIME:20210326T100000Z
DTSTAMP;VALUE=DATE-TIME:20240423T105100Z
UID:BeijingMoscowColloquium/13
DESCRIPTION:Title: Introduction to p-adic Langlands program for GL_2\nby
Hu Yongquan (Morningside Center of Mathematics\, Academy of Mathematics a
nd Systems Science) as part of Beijing Moscow Mathematics Colloquium\n\n\n
Abstract\nThe $p$-adic and mod $p$ Langlands program is an avatar of the c
lassical Langlands program and has been first initiated by C. Breuil. In t
his colloquium talk\, I will give a brief introduction to the program and
survey some recent progress in the case of $GL_2$.\n\nMeeting ID: 673 7981
0561\nPassword：263867\n
LOCATION:https://researchseminars.org/talk/BeijingMoscowColloquium/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Anton Trushechkin (Steklov Mathematical Institute of RAS)
DTSTART;VALUE=DATE-TIME:20210409T080000Z
DTEND;VALUE=DATE-TIME:20210409T090000Z
DTSTAMP;VALUE=DATE-TIME:20240423T105100Z
UID:BeijingMoscowColloquium/14
DESCRIPTION:Title: Mathematical methods of quantum key distribution\nby
Anton Trushechkin (Steklov Mathematical Institute of RAS) as part of Beiji
ng Moscow Mathematics Colloquium\n\n\nAbstract\nQuantum key distribution a
nd\, more generally\, quantum cryptography is a modern branch of science w
here methods of secure communication based on principles of quantum mechan
ics are studied. The rigorous proof of the security of quantum key distrib
ution gave rise to a complex and beautiful mathematical theory\, which is
based on methods of quantum information theory\, namely\, quantum entropi
c measures and entropic uncertainty relations. In particular\, to estimate
secret key rate\, one needs to minimize the quantum relative entropy (a c
onvex function) subject to linear constraints. The problem is\, in general
\, infinite-dimensional\, but symmetry properties of the problem reduces t
he dimensionality and allows one to solve this problem analytically. Howev
er\, currently\, an important task is to prove the security of quantum key
distribution with imperfect (i.e.\, practical) devices. Imperfections int
roduce asymmetries and thus make the problem more complicated. In the talk
\, estimations for the secret key rate in the case of detection-efficiency
mismatch will be presented. Using entropic uncertainty relations\, an inf
inite-dimensional problem is reduced to a one-dimensional one.\n\nMeeting
ID:633 6361 1209\nPassword: 127853\n
LOCATION:https://researchseminars.org/talk/BeijingMoscowColloquium/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Feihu Xu (University of Science and Technology of China)
DTSTART;VALUE=DATE-TIME:20210409T090000Z
DTEND;VALUE=DATE-TIME:20210409T100000Z
DTSTAMP;VALUE=DATE-TIME:20240423T105100Z
UID:BeijingMoscowColloquium/15
DESCRIPTION:Title: A quantum leap in security\nby Feihu Xu (University o
f Science and Technology of China) as part of Beijing Moscow Mathematics C
olloquium\n\n\nAbstract\nQuantum cryptography or quantum key distribution
(QKD) offers information-theoretic security based on the laws of physics.
This is the technology at the basis of the quantum satellite "Mozi"\, put
in orbit by the Chinese Academy of Sciences in 2016. In practice\, however
\, the imperfections of realistic devices might introduce deviations from
the idealized models used in the security proofs of QKD. Can quantum code
breakers successfully hack real systems by exploiting the side channels? C
an quantum code makers design innovative countermeasures to foil quantum c
ode breakers? In this talk\, I will talk about the theoretical and experim
ental progress in the practical security aspects of quantum code making an
d quantum code breaking. After numerous attempts over the past decades\, r
esearchers now thoroughly understand and are able to manage the practical
imperfections. Recent advances\, such as the decoy-state\, measurement-dev
ice-independent (MDI) and twin-field (TF) protocols\, have closed critical
side channels in the physical implementations in a rigorous and practical
manner. Further readings in [Xu et al.\, Rev. Mod. Phys. 92\, 025002 (202
0)].\n\nMeeting ID: 633 6361 1209\nPassword: 127853\n
LOCATION:https://researchseminars.org/talk/BeijingMoscowColloquium/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alexander Guterman (Moscow State University)
DTSTART;VALUE=DATE-TIME:20210423T080000Z
DTEND;VALUE=DATE-TIME:20210423T090000Z
DTSTAMP;VALUE=DATE-TIME:20240423T105100Z
UID:BeijingMoscowColloquium/16
DESCRIPTION:Title: Values of permanent and positive solution of Wang-Krauter
problem\nby Alexander Guterman (Moscow State University) as part of B
eijing Moscow Mathematics Colloquium\n\n\nAbstract\nThe talk is based on t
he joint work with M.V. Budrevich.\n\nThe class of $(-1\,1)$-matrices is v
ery important in algebra and combinatorics and in various their applicatio
ns. For example\, well-known\n Hadamard matrices are of this type.\n\nAn i
mportant matrix function is the permanent:\n$$\n{\\rm per}\\\, A= \\sum_
{\\sigma\\in { S}_n} a_{1\\sigma(1)}\\cdots a_{n\\sigma(n)}\, $$\nhere $A
=(a_{ij})\\in M_n({\\mathbb F})$ is an $n\\times n$ matrix over a field ${
\\mathbb F}$ and $S_n$ denotes the set of all permutations of the set $\\{
1\,\\ldots\, n\\}$.\n\nWhile the computation of the determinant can be don
e in a polynomial time\, it is still an open question\, if there are such
algorithms to compute the permanent.\n\nIn this talk we discuss the perman
ents of $\\pm 1$-matrices.\n\n\nIn 1974 Wang posed a problem to find a dec
ent upper bound for $|{\\rm per}(A)|$ if $A$ is a square $\\pm 1$-matrix o
f rank $k$. In 1985 Krauter conjectured some concrete upper bound.\n\nWe p
rove the Krauter's conjecture and thus obtain the complete answer to the W
ang's question. In particular\, we characterized matrices with the maximal
possible permanent for each value of $k$.\n\nMeeting ID: 645 6321 1865\nP
assword：341825\n
LOCATION:https://researchseminars.org/talk/BeijingMoscowColloquium/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Chuanming Zong (Tianjin University)
DTSTART;VALUE=DATE-TIME:20210423T090000Z
DTEND;VALUE=DATE-TIME:20210423T100000Z
DTSTAMP;VALUE=DATE-TIME:20240423T105100Z
UID:BeijingMoscowColloquium/17
DESCRIPTION:Title: From Sphere Packings to Post-Quantum Cryptography\nby
Chuanming Zong (Tianjin University) as part of Beijing Moscow Mathematics
Colloquium\n\n\nAbstract\nIn 1611\, Kepler made the following conjecture:
In three dimensions\, the density of the densest sphere packing is $\\pi/
\\sqrt{18}$. Through the works of Newton\, Gauss\, Hilbert\, Minkowski and
others\, sphere packings has been developed into an important mathematica
l discipline between number theory and geometry. In 1940s\, the methods an
d results of sphere packings had been applied into information theory by S
hannon\, Hamming and others. Around 2000\, lattice sphere packings surpris
ingly found applications in modern cryptography. In particular\, Shor\, Aj
tai\, Pipher and others applied it into post-quantum cryptography. In this
talk\, we will briefly introduce this dramatic development.\n\nMeeting ID
: 645 6321 1865\nPassword：341825\n
LOCATION:https://researchseminars.org/talk/BeijingMoscowColloquium/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Stefan Nemirovski (Steklov Mathematical Institute of RAS)
DTSTART;VALUE=DATE-TIME:20210514T080000Z
DTEND;VALUE=DATE-TIME:20210514T090000Z
DTSTAMP;VALUE=DATE-TIME:20240423T105100Z
UID:BeijingMoscowColloquium/18
DESCRIPTION:Title: Lorentz geometry and contact topology\nby Stefan Nemi
rovski (Steklov Mathematical Institute of RAS) as part of Beijing Moscow M
athematics Colloquium\n\n\nAbstract\nRoger Penrose observed four decades a
go that the space of light rays of a reasonable spacetime carries a natura
l contact structure and raised the problem of describing the causality rel
ation of the spacetime in its terms. The talk will survey the progress mad
e in this direction from the seminal work of Robert Low to the more recent
applications of global contact rigidity.\n\nZoom meeting ID: 649 3888 863
0\nPassword：774874\n
LOCATION:https://researchseminars.org/talk/BeijingMoscowColloquium/18/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Wenshuai Jiang (Zhejiang University)
DTSTART;VALUE=DATE-TIME:20210514T090000Z
DTEND;VALUE=DATE-TIME:20210514T100000Z
DTSTAMP;VALUE=DATE-TIME:20240423T105100Z
UID:BeijingMoscowColloquium/19
DESCRIPTION:Title: Gromov-Hausdorff limit of manifolds and some applications
\nby Wenshuai Jiang (Zhejiang University) as part of Beijing Moscow Ma
thematics Colloquium\n\n\nAbstract\nGromov-Hausdorff distance is a distanc
e between two metric spaces\, which was introduced by Gromov 1981. From Gr
omov's compactness theorem\, we knew that any sequence of manifolds with u
niform lower Ricci curvature bounds has a converging subsequence in Gromov
-Hausdorff topology to a limit metric space. The limit metric space in ge
neral may not be a manifold. The structure of such limit metric space has
been studied by Cheeger\, Colding\, Tian\, Naber and many others since 199
0. It turns out that such theory has powerful application in geometry. In
fact\, the resolution of Yau-Tian-Donaldson conjecture was largely relied
on the development of the study of the limit metric space.\n\nIn the first
part of the talk\, we will discuss some recent progress of the Gromov-Hau
sdorff limit of a sequence of manifolds with Ricci curvature bounds. In th
e second part\, we will discuss some applications based on the study of Gr
omov-Hausdorff limits.\n\nZoom Meeting ID: 649 3888 8630\nPassword：77487
4\n
LOCATION:https://researchseminars.org/talk/BeijingMoscowColloquium/19/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ivan Polekhin (Steklov Mathematical Institute of RAS)
DTSTART;VALUE=DATE-TIME:20210521T080000Z
DTEND;VALUE=DATE-TIME:20210521T090000Z
DTSTAMP;VALUE=DATE-TIME:20240423T105100Z
UID:BeijingMoscowColloquium/20
DESCRIPTION:Title: On the application of the Ważewski method to the problem
of global stabilization\nby Ivan Polekhin (Steklov Mathematical Insti
tute of RAS) as part of Beijing Moscow Mathematics Colloquium\n\n\nAbstrac
t\nIn 2000\, S.P. Bhat and D.S. Bernstein proved that if the configuratio
n space of an autonomous control mechanical system is closed (compact with
out boundary)\, then the system cannot have a globally asymptotically stab
le equilibrium [1]. We will present a similar result for non-autonomous co
ntrol systems defined on manifolds with non-empty boundaries. The talk is
based on the paper [2].\n\n[1] Bhat S.P.\, Bernstein D.S. A topological ob
struction to continuous global stabilization of rotational motion and the
unwinding phenomenon Systems Control Lett.\, 39 (1) (2000)\, pp. 63-70\n\n
[2] I. Polekhin\, "On the application of the Ważewski method to the prob
lem of global \nstabilization"\, Systems & Control Letters\, 153 (2021) Sh
are Link: https://authors.elsevier.com/a/1d2Qoc8EXim67\n\nMeeting ID: 854
8688 3613 \nPassword: 303680\n
LOCATION:https://researchseminars.org/talk/BeijingMoscowColloquium/20/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yaomin Zhao (College of Engineering\, Peking University)
DTSTART;VALUE=DATE-TIME:20210521T090000Z
DTEND;VALUE=DATE-TIME:20210521T100000Z
DTSTAMP;VALUE=DATE-TIME:20240423T105100Z
UID:BeijingMoscowColloquium/21
DESCRIPTION:Title: High Fidelity Simulations of High-Pressure Turbines Casca
des for Data-Driven Model Development\nby Yaomin Zhao (College of Engi
neering\, Peking University) as part of Beijing Moscow Mathematics Colloqu
ium\n\n\nAbstract\nGas turbines (GT) are\, and will continue to be\, the b
ackbone of aircraft propulsion\, as well as power generation and mechanica
l drive. A small GT performance improvement is expected to have a fuel-spe
nd advantage of the billion-dollar order\, together with a significant CO2
emission benefit. Part of the possible performance improvements can be en
abled by continuously advancing the understanding of the GT flow physics a
nd thus further reducing the inaccuracy of current design tools based on c
omputational fluid dynamics (CFD). By exploiting the capability of our hig
h-fidelity CFD solver on leadership GPU-accelerated supercomputers\, we ha
ve been able to perform state-of-the-art high fidelity simulations of turb
omachinery flows. The generated data\, therefore\, can shed light on the d
etailed fundamental flow physics\, in particularly the behavior of transit
ional and turbulent boundary layers affected by large-scale violent freest
ream turbulence\, under strong pressure gradient and curvature. Furthermor
e\, machine learning methods are applied to the high-fidelity data to deve
lop low order models readily applicable to GT designs.\n\nMeeting ID: 854
8688 3613 \nPassword: 303680\n
LOCATION:https://researchseminars.org/talk/BeijingMoscowColloquium/21/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Andrei Zotov (Steklov Mathematical Institute of Russian Academy of
Sciences)
DTSTART;VALUE=DATE-TIME:20210604T080000Z
DTEND;VALUE=DATE-TIME:20210604T090000Z
DTSTAMP;VALUE=DATE-TIME:20240423T105100Z
UID:BeijingMoscowColloquium/22
DESCRIPTION:Title: Integrable systems with elliptic dependence on momenta an
d related topics\nby Andrei Zotov (Steklov Mathematical Institute of R
ussian Academy of Sciences) as part of Beijing Moscow Mathematics Colloqui
um\n\n\nAbstract\nWe discuss a family of integrable many-body systems of c
lassical (and quantum) mechanics. Some interrelations (dualities) predict
existence of integrable many-body systems with elliptic dependence on part
icles momenta – the most general representative of this family. We descr
ibe some recent results on this topic. Next\, we discuss relations of the
many-body systems to other families of integrable models including integra
ble tops and spin chains. Finally\, some interesting open problems are for
mulated.\n\nMeeting ID: 831 2285 8822\nPassword: 338416\n
LOCATION:https://researchseminars.org/talk/BeijingMoscowColloquium/22/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Wenli Yang
DTSTART;VALUE=DATE-TIME:20210604T090000Z
DTEND;VALUE=DATE-TIME:20210604T100000Z
DTSTAMP;VALUE=DATE-TIME:20240423T105100Z
UID:BeijingMoscowColloquium/23
DESCRIPTION:Title: Off-diagonal Bethe ansatz approach to quantum integrable
models\nby Wenli Yang as part of Beijing Moscow Mathematics Colloquium
\n\n\nAbstract\nApplying the recent developed method-the off-diagonal Beth
e ansatz method\, we construct the exact solutions of the Heisenberg spin
chain with various boundary conditions. The results allows us to calculate
the boundary energy of the system in the thermo dynamic limit. The method
used here can be generalized to study the thermodynamic properties and bo
undary energy of other high rank models with non-diagonal boundary fields.
\n\nMeeting ID: 831 2285 8822\nPassword: 338416\n
LOCATION:https://researchseminars.org/talk/BeijingMoscowColloquium/23/
END:VEVENT
END:VCALENDAR