Abstract:
In the talk, I understand a diagram as a topological space
obtained by gluing a finite number of pairwise non-intersecting
rectangles along their sides to a standard circle, equipped with
the following two structures. First, a point is chosen and fixed on
the circle outside the glued rectangles. Second, the standard
orientation is fixed on the circle. (It is assumed that after gluing
the rectangles to the circle, the images of different rectangles do
not intersect each other and that the images of the complements
to the sides of the rectangles do not intersect with the circle.)
The main goal of the talk is to introduce the equivalence
relation needed for tangle theory on the set of diagrams and to
study its simplest properties. This equivalence relation is, as far
as the author knows, new, that is, it has not been met or studied
in the scientific literature.
Zoom (new link!): https://zoom.us/j/97302991744 Access code: the Euler characteristic of the wedge of two circles
(the password is not the specified phrase but the number that it determines)