26-06-2019 |
Dilip Patil, IISc, Bangalore: Mathematics Colloquium |
On the number of rational points on real algebraic varieties.
he main result of this colloquium is the equality of the
number of K-rational points with the signature of the trace form of a
finite K-algebra over a real closed field K. The main tools are symmetric
bilinear forms, Hermitian forms, trace forms, generalized trace forms and
their types and signatures. Further, we prove a criterion for the
existence of K-rational points by using generalized trace forms. As an
application we prove the Pederson-Roy-Szpirglas theorem about counting
common real zeros of real polynomial equations.
|
|
21-06-2019 |
Dr. Uday Sharma, IISER Pune |
Simultaneous conjugacy classes of commuting tuples
In this seminar, I will talk about the classification of tuples
of commuting matrices over a finite field, upto simultaneous conjugation.
|
|
06-06-2019 |
Srikanth Srinivasan |
Algebraic complexity theory and connections to Hilbert functions
(Lecture III).
In a few lectures, I will introduce some of the main
problems in Algebraic Complexity theory and some of the techniques
that have been used to make progress on them. The techniques are
closely related to Hilbert functions and Young flattenings.
|
|
03-06-2019 |
Madhu Sudan (Harvard University) |
Communication Complexity of Randomness Manipulation
The task of manipulating randomness has been a subject of
intense investigation in computational complexity with dispersers,
extractors, pseudorandom generators, condensers, mergers being just a
few of the objects of interest. All these tasks consider a single
processor massaging random samples from an unknown source.
In this talk I will talk about a less studied setting where randomness
is distributed among different players who would like to convert this
randomness to others forms with relatively little communication. For
instance players may be given access to a source of biased correlated
bits, and their goal may be to get a common random bit out of this
source. Even in the setting where the source is known this can lead to
some interesting questions that have been explored since the 70s with
striking constructions and some suprisingly hard questions. After
giving some background, I will describe a recent work which explores
the task of extracting common randomness from correlated sources with
bounds on the number of rounds of interaction.
Based on joint work with Mitali Bafna (Harvard), Badih Ghazi (Google)
and Noah Golowich (Harvard).
|
|
30-05-2019 |
Srikanth Srinivasan |
Algebraic complexity theory and connections to Hilbert functions
(Lecture II).
In a few lectures, I will introduce some of the main
problems in Algebraic Complexity theory and some of the techniques
that have been used to make progress on them. The techniques are
closely related to Hilbert functions and Young flattenings.
|
|
20-05-2019 |
Srikanth Srinivasan |
Algebraic complexity theory and connections to Hilbert functions.
In a few lectures, I will introduce some of the main
problems in Algebraic Complexity theory and some of the techniques
that have been used to make progress on them. The techniques are
closely related to Hilbert functions and Young flattenings.
|
|
16-05-2019 |
Raj Kamal Maurya, IIT Patna |
Some Problems of Estimation and Prediction under Progressive
Censoring.
: We have considered the problem of making statistical inferences for different lifetime
models on the basis of progressive type-II censored samples. In particular, we have
derived various estimates of parameters using both classical and Bayes methods. The
associated MLEs are computed using the EM algorithm. We also compute the ob-
served Fisher information matrices and based on these computations, the asymptotic
confidence intervals of parameters are constructed. Bootstrap intervals are also dis-
cussed. We also derive Bayesian estimates of parameters against different loss func-
tions. Most of these estimates appear in analytically intractable forms and so we
have used different approximation methods like importance sampling, Lindley, Tier-
ney and Kadane procedures to compute the Bayes estimates. In sequel, we have also
constructed highest posterior density intervals of parameters. We have also derived
predictive inference for censored observations under frequentist and Bayesian frame-
works. In particular, we obtain best unbiased predictor, conditional median predictor
from frequentist perspective. Among prediction intervals, we construct pivotal in-
terval, highest conditional density interval, equal tail interval and HPD interval for
future observations. Determination of optimal plans is one of the primary objective
in many life test studies. We have obtained such plans again using both frequentist
and Bayesian approaches under progressive censoring. We also consider estimation
of multicomponent stress-strength reliability under progressive censoring. We have
numerically compared the proposed methods using simulations for each problem. We
have also discussed real life examples in support of studied methods. We have provided
relevant information in each chapter of the thesis.
|
|
17-05-2019 |
R. Parimala, Emory University, Mathematics Colloquium. |
Norm equations and local-global principles.
Let L be a cyclic extension of a number field K. Hasse’s theorem
says that
an element of K is a norm from L if it is a norm locally at all
completions of K.
Examples of failure of similar local global principle if L is not cyclic
were also
known. We survey recent results on obstructions to local global principle
for norm
equations over number fields.
|
|
16-05-2019 |
Satya Mandal, University of Kansas |
Homotopy obstructions for Projective Modules.
The Theory for vector bundles in topology shaped the research in
projective modules in algebra, consistently. This includes Obstruction
Theory. The
algebra has always been trying to catch up. To an extent, this fact
remained under
appreciated.
For an affine scheme $X=\spec{A}$, and a projective $A$-module $P$, our
objective
would be to define an obstruction class $\varepsilon(P)$ in a suitable
obstruction
house (preferably a group), so the triviality of $\varepsilon(P)$ would
imply $P
\equiv Q \oplus A$. One would further hope the obstruction house is an
invariant of
$X$; not of $P$. We would report on what is doable. We detect splitting $P
\equiv Q
\oplus A$ by homotopy.
|
|
14-05-2019 |
Jyoti Singh, Visvesvaraya National Institute of Technology, Nagpur |
Strongly generalized Eulerian $D$-modules
Let K be a field of characteristic zero and A_n(K) be the nth-Weyl
algebra over K. In this talk, we discuss strongly generalised Eulerian
$A_n(K)$-modules and their properties. We prove that if M is a strongly
generalized
Eulerian $A_n(K)$-module, then so is the graded Matlis dual of M. We also
prove that
Ext functor of strongly generalized Eulerian modules is strongly generalized
Eulerian $A_n(K)$-module. As a consequence, we prove the following
conjecture:
Let M and N be non-zero, left, holonomic, graded generalized Eulerian
$A_n(K)$-modules. Then the graded K-vector space $Ext^i_{A_n(K)}(M, N)$ is
concentrated in degree zero for any i >=0.
|
|
First Previous 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Next Last |