Of Torus and Turk's-Head Knots: A Polar Trigonometric Modeling
The following problem is investigated: «Find an elementary function such that if is a knot diagram with crossings and the corresponding knot is trivial, then there is a sequence of Reidemeister moves that proves triviality such that at each step we have less than crossings». The problem is shown to be equivalent to a problem posed by D. Welsh in [7] and solved by geometrical techniques (normal surfaces).
Józef Przytycki introduced skein modules of 3-manifolds and skein deformation initiating algebraic topology based on knots. We discuss the generalized skein modules of Walker, defined by fields and local relations. Some results by Przytycki are proven in a more general setting of fields defined by decorated cell-complexes in manifolds. A construction of skein theory from embedded TQFT-functors is given, and the corresponding background is developed. The possible coloring of fields by elements of...
Let be a non-trivial knot in the -sphere, its exterior, its group, and its peripheral subgroup. We show that is malnormal in , namely that for any with , unless is in one of the following three classes: torus knots, cable knots, and composite knots; these are exactly the classes for which there exist annuli in attached to which are not boundary parallel (Theorem 1 and Corollary 2). More generally, we characterise malnormal peripheral subgroups in the fundamental group of a...