18-10-2018 |
Parvez Sarwar |
Algebraic K-theory and homology stability
We shall begin with the homotopy invariance property of
K-theory. After reviewing monoids and monoid algebras, we present some
results which are monoid version of the homotopy invariance property in
K-theory. This answers a question of Gubeladze. Next, we will discuss the
monoid version of Weibel's vanishing conjecture and some results in this
direction. Finally, we will talk about the homology stability for groups.
Here we present a result which improves homology stability for symplectic
groups. If the time permits, some application of the homology stability
will be given to the hermitian K-theory.
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18-10-2018 |
Debanjana Mitra |
Control of wave equation.
In this talk, we will mainly discuss on the control of wave
equation. At the first part of the talk, we will give an overview of the
control of wave equation and mention some important results in this
direction. Then in the second part, the control of wave equation using
Hilbert uniqueness method will be discussed.
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17-10-2018 |
Department Colloquium |
An overview of the theory of Hypocoercivity.
In this talk, we attempt to give a brief introduction to the
theory of Hypocoercivity which has become an indispensable tool in the
study of relaxation to equilibrium states for mathematical models arising
in statistical physics. The essential ideas behind this theory will be
motivated via simple examples. The role of certain functional inequalities
while deriving explicit rates of convergence will be made precise during
this talk. This talk concludes by addressing a certain degenerate kinetic
Fokker-Planck equation. Incidentally, the study of the trend to
equilibrium for this degenerate model finds link to the acclaimed
Geometric Condition from the theory of control for wave propagation.
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17-10-2018 |
Somnath Jha |
A duality for Selmer groups
Selmer group is an important object of study in number theory.
We will discuss a twisting result in the setting of so called
"non-commutative" Iwasawa theory. We will further use this to deduce a
duality result for certain Selmer groups. (This talk is based on joint
works with T. Ochiai, G. Zabradi and S. Shekhar.
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16-10-2018 |
Neeraj Kumar |
Wilf's conjecture on numerical semigroups
The aim of the talk is to give a brief survey on the Wilf's
conjecture, and to present a commutative algebra formulation of it. We
will verify Wilf's conjecture in some cases.
A numerical semigroup $S$ is a subset of the nonnegative integers $N$ that
is closed under addition, contains 0, and has finite complement in $N$.
The Frobenius number $F$ of numerical semigroup $S$ is the largest integer
not in $S$. Let $d$ be the minimal number of generators of $S$ and $n$ be
the number of representable integers in the interval $[0, F]$. Wilf's
conjecture states that $F +1 \leq n d$.
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15-10-2018 |
Prof. Palash Ghosh Centre for Quantitative Medicine DUKE-NUS Medical School National University of Singapore |
Dynamic Generalized Odds-Ratio (dGOR): A novel approach to assess
Dynamic Treatment Regimes (DTR) with An Ordinal Outcome.
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15-10-2018 |
Prof. Jerome Droniou |
What the second Strang lemma and the Aubin-Nitsche trick should be
The second Strang lemma gives an error estimate for linear
problems written in variational formulation, such as elliptic equations.
It covers both conforming and non-conforming methods, it is widely spread
in the finite element community, and usually considered as the starting
point of any convergence analysis.
For all its potency, it has a number of limitations which prevents its
direct application to other popular methods, such as dG methods, Virtual
Element Methods, Hybrid High Order schemes, Mimetic Methods, etc. Ad-hoc
adaptations can be found for some of these methods, but no general `second
Strang lemma' has been developed so far in a framework that covers all
these schemes, and others, at once.
In this talk, I will present a `third Strang lemma' that is applicable to
any discretisation of linear variational problems. The main idea to
develop a framework that goes beyond FEM and covers schemes written in a
fully discrete form is to estimate, in a discrete energy norm, the
difference between the solution to the scheme and some interpolant of the
continuous solution. I will show that this third Strang lemma is much
simpler to prove, and use, than the second Strang lemma. It also enables
us to define a clear notion of consistency, including for schemes for
which such a notion was not clearly defined so far, and for which the Lax
principle `stability + consistency implies convergences' holds.
I will also extend the analysis to the Aubin-Nitsche trick, presenting a
generalisation of this trick that covers fully discrete schemes and
provides improved error estimates in a weaker norm than the discrete
energy norm. We will see that the terms to estimate when applying this
Aubin-Nitsche trick are extremely similar to those appearing when applying
the third Strang lemma; work done in the latter case can therefore be
re-invested when looking for improved estimates in a weaker norm.
I will conclude by briefly presenting applications of the third Strang
lemma and the abstract Aubin-Nitsche trick to discontinuous Galerkin and
Finite Volume methods.
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08-10-2018 |
Dr. Kunal Dutta |
A file with the title and abstract of his talk is attached
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12-10-2018 |
Samala Rathan, VNIT, Nagpur |
"High-resolution shock capturing high-order WENO schemes for hyperbolic conservation laws"
"In this talk, we present a class of new higher order WENO spatial approximation
schemes to solve the hyperbolic conservation laws along with the use of total
variation diminishing (TVD)/strong stability preserving Runge-Kutta (SSPRK)
temporial derivative approximation techniques. The objective of these developments
aim for the improvements, in obtaining higher resolution and efficiency of the
solution which retains the desired order of accuracy in smooth regions and in the
presence of critical points. These improvements have been achieved by mainly
focusing on the construction of new smoothness indicators which plays a key role in
the spatial derivative approximation of flux function via the nonlinear weights in WENO
algorithm. With these new measurements, higher-order WENO schemes viz fifth and
seventh-order WENO schemes have been constructed and subsequently imposed a
sufficient condition on the parameters in the weight functions which recovers the
optimal order for smooth regions of solution that includes the critical points.
Numerical results show that these new schemes achieve optimal-order of accuracy.
These schemes also show the advantage of resolving the sharper results for shock
waves, contact discontinuities and the regions that contain high-frequency waves."
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11-10-2018 |
R.V.Gurjar |
Complete modules and base conditions of linear system.
We will discuss Zariski's theory of complete modules and their
relation to base points of linear systems.
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