


Algebraic Stacks lecture series
Tuesday, 13 February, 11:30 AM
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Venue: Ramanujan Hall
Host: Sudarshan Gurjar
Speaker: Nitin Nitsure
Affiliation: Bhaskaracharya Pratishthana
Title: Separated and proper morphisms for algebraic stacks.
Abstract: We will begin by revisiting the valuative criteria for universal closedness and separateness for morphisms between schemes. This will be followed by interesting elementary examples that illustrate why these criteria do not directly apply to algebraic spaces and algebraic stacks. We will end with the modified criteria that apply to algebraic spaces and algebraic stacks.
Topology and Related Topics Seminar
Tuesday, 13 February, 12:001:00
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Venue: Ramanujan Hall (Hybrid Lecture) (Speaker will be online).
Host: Rekha Santhanam
Speaker: Suraj Krishna
Affiliation: Technion  Israel Institute of Technology
Title: Mapping tori in geometric group theory.
Abstract: In this talk, I will provide a gentle introduction to
geometric group theory using the concept of mapping tori. Using pictures
and examples, I will introduce the relevant topics and give a glimpse of
some of the spectacular progress made by stalwarts like Bill Thurston.
Additionally, I will mention some recent progress in the field, along
with my forays.
This talk is a background lecture especially aimed at graduate students
for the talk Suraj Krishna will give the following Tuesday.
Commutative Algebra Seminar
Tuesday, 13 Feb, 3 pm—4 pm
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Venue: Room 215
Host: Tony J. Puthenpurakal
Speaker: Sudeshna Roy
Affiliation: TIFR Bombay
Title: Epsilon multiplicity in twodimensional standard graded algebras
Abstract: The notion of epsilon multiplicity, a generalization of the HilbertSamuel multiplicity, was introduced by B. Ulrich and J. Validashti to detect the integral dependence of arbitrary ideals. This invariant is difficult to handle as there are examples where it can be irrational and the epsilon function is very far from being polynomiallike. Let $A$ be a standard graded normal domain of dimension two over a field with the unique homogeneous maximal ideal $m$. Let $I$ be a homogeneous ideal in $A$. Our objective is to show that the epsilon multiplicity of $I$ is a rational number.
Algebraic Groups Seminar
Tuesday, February 13, 4 PM5 PM
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Venue: Ramanujan Hall, Department of Mathematics
Host: Dipendra Prasad
Speaker: Mohammed Saad Qadri
Affiliation: IIT Bombay
Title: Regular elements in semisimple algebraic groups
Abstract: We will discuss the paper by Robert Steinberg, Regular elements of semisimple algebraic groups Publications mathématiques de l'I.H.É.S., tome 25 (1965), p. 4980.
Commutative Algebra seminar
Tuesday, 13 February 4 pm5 pm
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Venue: Ramanujan Hall
Host: J. K. Verma
Speaker: S. K. Khanduja
Affiliation: IISER Mohali
Title: Some wellknown Irreducibility Criteria for polynomials over rationals and their generalizations
Abstract: We will review the classical irreducibility criteria of Eisenstein, Schoenemann, and Dumas, and then discuss their extensions using Newton polygons and the theory of valuations. We shall also present recently proved generalizations of the wellknown
results of Schur as well as of Filaseta and Trifonov regarding the irreducibility of the truncated exponential polynomial and the Bessel polynomial. This talk is partly based on joint work with Ankita Jindal, Bablesh Jhorar, and Sanjeev Kumar.