11. Actually, string figures are " unknots " or " trivial " knots. 12. The special case of recognizing the unknot , called the unknotting problem, is of particular interest. 13. The simplest such invariant is tricolorability : the trefoil is tricolorable, but the unknot is not. 14. In three dimensions, the unknot cannot be written as the sum of two non-trivial knots. 15. The crosscap number of the unknot is zero, as the Euler characteristic of the disk is one. 16. It is an open problem whether any non-trivial knot has the same Jones polynomial as the unknot . 17. However, there are invariants which distinguish the unknot from all other knots, such as Khovanov homology and knot Floer homology. 18. In addition, virtually every major knot polynomial distinguishes the trefoil from an unknot , as do most other strong knot invariants. 19. Since V is an unknotted solid torus, S ^ 3 \ setminus V is a tubular neighbourhood of an unknot J. 20. Claw moved the log closer to the gate to make it easier to unknot , while Sting went to the finish line.
