bidyut sanki
Assistant Professor
Research Area - Low-dimensional Topology and Geometry
Research Interests
Low-dimensional topology and geometry.
In particular
Hyperbolic Geometry
Teichm ̈uller theory
Mapping class groups
Moduli spaces
Topological graph theory
Differential topology
Combinatorial topology
Systolic topology and geometry
Publications
Published:
Filling with separating curves (with B N Saha)
Journal of Topology and Analysis, arXiv:2301.05840 (2024)
DOI: Coming soon.
Filling systems on surfaces (with Shiv Parsad)
Journal of Topology and Analysis, arXiv:1708.06928
DOI. https://doi.org/10.1142/S1793525324500055 (2023)
Self-intersecting filling curves on surfaces (with Shiv Parsad)
Journal of Knot Theory and its ramification (JKTR), Vol 31, No. 07, 2250050 (2022)
https://doi.org/10.1142/S021821652250050X
A Conjecture on the Lengths of Filling Pairs (with Arya Vadnere)
Geometriae Dedicata, Volume 213, issue 1, 359-373(2021).
DOI: 10.1007/s10711-020-00586-8
Geometric realizations of cyclic actions on surfaces (with Shiv Parsad, Kashyap Rajeevsarathy)
Journal of Topology and Analysis, vol 11, No. 04, pp. 929 - 964 (December, 2019),
DOI–10.1142/S1793525319500365
Embedding of metric graphs on hyperbolic surfaces
Bulletin of the Australian Mathematical Society, Volume 99, Issue 3, pp. 508–520, (June, 2019),
DOI–10.1017/S0004972719000145
Graphs of systoles on hyperbolic surfaces (with Siddhartha Gadgil)
Journal of Topology and Analysis, vol 11, No. 01, pp. 1 - 20 (March, 2019),
DOI–10.1142/S1793525319500018
Filling of closed surfaces
Journal of Topology and Analysis, Vol. 10, No. 04, pp. 897 - 913 (December, 2018),
DOI 10.1142/S1793525318500309
Systolic fillings of surfaces
Bulletin of the Australian Mathematical Society, Volume 98, Issue 3, pp. 502–511, (December 2018),
DOI–10.1017/S0004972718000862
Arxiv version: Not available
Preprints:
Contact Information
Email ID: bidyut@iitk.ac.in
Office Phone: 0512-259-2085
Office Address: Room no 587, Faculty Building
Education
PhD, Department of Mathematics, IISc Bangalore, India, (August 2009 - July 2014).
Thesis Title: Shortest length geodesics on closed hyperbolic surfaces.
Thesis Advisor - Prof. Siddhartha Gadgil.
MSc, Department of Mathematics and Statistics, IIT Kanpur, India, August 2007 - July 2009
BSc, Jadavpur University, Kolkata, India, 2004 - 2007
Experience
Assistant Professor, Department of Mathematics and Statistics, IIT Kanpur
November, 2018 to Present
Postdoctoral Fellow, IMSc, Chennai.
December, 2016 - November, 2018
Postdoctoral Fellow, IISER Bhopal.
August, 2016 – December, 2016.
Postdoctoral Fellow, RKMVERI, Belur.
July, 2015 - July, 2016.
Research Associate, IISc Bangalore.
August 2014 - June 2015.
Teaching
Current Semester: (MTH114M) Ordinary differential equations
Lecture notes:
Lecture 1: Definitions, examples, geometric interpretation, orthogonal and oblique trajectories
Lecture 2: IVP, Separable of variables, reducible to separable, exact equations.
Lecture 3: Exact ODEs, integrating factors
Lecture 4: Linear ODEs, Bernoulli's equation, reducible second order ODEs
Lecture 6: Numerical methods: Euler's method and Improved Euler's method; Second order linear ODEs
Lecture 7: Wronskian, solution space of 2nd order homogeneous linear ODEs, Fundamental system
Lecture 9: Non-homogeneous linear equations: Method of undetermined coefficients
Past.
Algebraic topology (I) MTH649A
Semester: 2023-24(I)
Lecture notes.
Lecture 5: Path homotopy fixing endpoints and Fundamental Groupoid
Lecture 6: Algebraic properties of path homotopy and Fundamental groups.
Lecture 7: Covering spaces, lifting problem, local lifting lemma, path lifting
Lecture 8: Path lifting lemma, homotopy lifting lemma and application
Mid-semester Exam:
Date and time: Sept 21, 2023, 18:00-20:00 hrs
Venue and seating plan: L9 ERES
15. Lecture 15: Seifert Van-Kampen Theorem
16. Lecture 16: Surfaces: Orientability, Connected sum and classification theorem.
18. Lecture 18: Surfaces: Triangulation, Euler characteristic, Fundamental group of Klein bottle, Graphs
19. Lecture 19: Graphs Euler characteristic of surface bounded above by 2, CW complex
22. Lecture 22: Deck transformation groups, Regular coverings, Covering space action
23. Lecture 23: Lifting properties, Classification of covering spaces
24. Lecture 24: Homology groups--Motivation and examples
25. Lecture 25: Simplicial homology
26. Lecture 26: Singular homology groups
Assignment 10
Final Exam: November 24, 2023 17:30--20:30 hrs
Venue and seating plan: L8, ERES
Introduction to Hyperbolic geometry (MTH633A)
Semester. 2022-23 (II)
Syllabus.
Refs.
J. Anderson, Hyperbolic Geometry, 1st ed., Springer Undergraduate Mathematics Series, Springer-Verlag, Berlin, New York, 1999.
S. Katok, Fuchsian Groups, Chicago Lecture Notes in Mathematics, Chicago University Press, 1992.
A. Beardon, The Geometry of Discrete Groups, Springer-Verlag, Berlin, New York, 1983.
MTH713A: Differential Topology
2020 - 2021, Semester II
Course Description: This is an introductory course in Differential Topology. The aim of this course is to introduce basic tools to study the topology and geometry of manifolds. We start with reviewing two key results from several variable calculus, namely the inverse function theorem and implicit function theorem which are essential to study differential manifolds. Throughout this course, we will discuss the theory of manifolds and a way to generalise differential, integral and vector calculus. By the end of the course, we should understand and able to work with manifolds, tangent and co-tangent bundles, transversality, Morse Lemma, Morse function, Whitney embedding theorem, Poincare – Hopf theorem, Sards theorem and its applications and many other things listed below in the course contents.
Course Contents:
Review of inverse function theorem and implicit function theorem.
Introduction to differential manifolds, sub-manifolds and manifolds with boundary.
Smooth maps between differential manifolds, tangent space, differential of smooth maps,
(local) diffeomorphism. Immersions, embeddings, regular value, level sets, submersions.
Tangent and cotangent bundles, vector bundles, vector fields, integral curves.
Transversality, Whitney embedding theorem, Sards theorem, Morse lemma, Morse
functions.
Oriented intersection Theory: degree, Lefchetz fixed point theory, the Poincare-Hopf
theorem, the Euler characteristic and triangulations (time permitting: Integration on manifolds).
Recommended books:
Differential Topology, Victor Guillemin and Alan Pollack (AMS Chelsea Book Series)
Topics in Differential Topology, Amiya Mukherjee (Hindustan Book Agency)
Topology from the Differentiable Viewpoint, John W. Milnor (Princeton University Press)
An Introduction to Differentiable Manifolds and Riemannian Geometry, William M.
Boothby (Elsevier)An introduction to manifolds, Loring W Tu (Springer).
MTH305A : Several variable calculus and differential geometry
2020 - 2021, Semester I
Syllabus:
Differentiation: Definition and examples, Mean value inequality, Tangent planes to level sets of functions; Implicit mapping theorem, Inverse mapping theorem and applications; Taylor's theorem and applications.
Curves: Definition and examples, Regular curves, Plane curves, Curvature of plane curves, Isoperimetric inequality for plane curves; Space curves, FrenetSerret formula for space curves; Local existence theorem curves.
Surfaces: Definition and examples; Tangent planes, Maps between surfaces; First fundamental and second fundamental forms; Curvature of surface; Hilbert's theorem for compact surfaces; Gauss theorem a Egregium.
References:
1. Spivak: Calculus on manifolds, Springer.
2. M P do Carmo: Differential geometry of curves and surfaces, Prentice Hall.
3. W. Rudin: Principles of Mathematical Analysis.
4. Tom M. Apostol: Mathematical Analysis, Narosa Publishing House, India.
5. A Pressley: Elementary differential geometry, Springer India.
Important Dates:
Course begins: September 1, 2020.
Ref. for first few lectures Chapter 1 and 2, Spivak: Calculus on manifolds
MTH 301A -Analysis I
2021-2022, Semester I
Summer Term 2021:
MTH305A: Several variables calculus \& differential geometry
Notes:
MTH304A : Topology
2019 - 2020, Semester II
MTH713A : Differential Topology
2019 - 2020, Semester I
MTH102A Tutor
2018 - 2019, Semester II
Group
PhD students
current.
1) Bhola Nath Saha
2) Achintya Dey (Joint with Dr Abhijit Pal)
UG Project students.
Current.
......
Past.
1) Nupur Jain 2022-23(I):
Topic: Topological graph theory
Major results-
Kuratowski's theorem,
Cayley Graphs and Frucht’s Theorem
Existence of regular graphs of a given Girth
MSc project students
Current.
Papiya Sur
Topic. Spherical Geometry
Past.
1) Arghys Sinha (2020-21): Report
Summer research programe:
1) Arya Vadnere (2019-20).
Topic. Aougab-Huang conjecture