# (−2,3,7) pretzel knot

(−2,3,7) pretzel knot
Arf invariant 0
Crosscap no. 2
Crossing no. 12
Hyperbolic volume 2.828122088
Unknotting no. 5
Conway notation [7;-2 1;2]
Dowker notation 4, 8, -16, 2, -18, -20, -22, -24, -6, -10, -12, -14
D-T name 12n242
Last /Next 12n241 12n243
Other
hyperbolic, fibered, pretzel, reversible

In geometric topology, a branch of mathematics, the (−2, 3, 7) pretzel knot, sometimes called the Fintushel–Stern knot (after Ron Fintushel and Ronald J. Stern), is an important example of a pretzel knot which exhibits various interesting phenomena under three-dimensional and four-dimensional surgery constructions.

## Mathematical properties

The (−2, 3, 7) pretzel knot has 7 exceptional slopes, Dehn surgery slopes which give non-hyperbolic 3-manifolds. Among the enumerated knots, the only other hyperbolic knot with 7 or more is the figure-eight knot, which has 10. All other hyperbolic knots are conjectured to have at most 6 exceptional slopes.

A pretzel (−2,3,7) pretzel knot.