Instructor: Dror Bar-Natan, drorbn@math.huji.ac.il, 02-658-4187.
Classes: Tuesdays 14:00-16:00 at Sprintzak 215.
Office hours: Sundays 14:00-15:00 in my office, Mathematics 309.
Web site: http://www.math.toronto.edu/~drorbn/classes/0001/KnotTheory/
Agenda: To learn about finite type knot invariants, and
especially about their multiply-proven but not-sufficiently-well
understood fundamental theorem, whose different proofs relate to
almost everything in mathematics.
More details: Finite type invariants are invariants of knots
that can be regarded, in a natural sense, as polynomials on the space
of all knots. It is a pretty powerful bunch of invariants, though they
are better liked for their beauty rather than their power. By the
fundamental theorem, they are classified by certain nice
combinatorial objects called chord diagrams (close relatives of the
Feynman diagrams of quantum field theory), modulo certain nice
relations that are deeply related to Lie algebras. In the first part of
the course we will talk about knots, knot invariants, finite type knot
invariants, chord diagrams and their basic algebraic properties, and
about the relationship with Lie algebras. We will then choose between
either one of two of the approaches to proving the fundamental
theorem, which, as we shall see, is equivalent to the construction of a
universal finite type invariant:
Key words and phrases: perturbation theory, Feynman diagrams,
configuration spaces, compactification, differential forms and Stokes'
theorem, degrees and general position, etc.
Some key formulas:
A key picture:
Key words and phrases: parenthesizations, associators, pentagons and hexagons, quasi-Hopf algebras, cohomology, PBW, triangulations and Pachner moves, planar algebras, etc.
Some key formulas: ![]() ![]() |
Some key pictures: ![]() ![]() |
Background image: A table of knots and links by Rob Scharein, taken from http://www.cs.ubc.ca/nest/imager/contributions/scharein/zoo/knotzoo.html.