The (-2,3,7) Pretzel knot
K may be obtained by Dehn surgery on
the minimally twisted five chain link, MT5C.
K will be the
core of one of the surgery solid tori. It is also an embedded curve on
the once-punctured torus fiber of the trefoil knot. Viewing this fiber
as the plumbing of two Hopf bands,
K may be obtained by Dehn
twisting the first core twice about the second and then Dehn twisting
this result twice about the original first core.
Quotienting each of these constructions by an involution, we may view
the exterior of
K as a ball containing a 2-string tangle as
the fixed set of the involution. The presentation as a "punctured"
3-strand braid
naturally arises from each of these constructions.
On the left, the colored arcs suggest the tangles filling four of the
boundary components of the quotiented exterior of the MT5C. On the
right, the colored arcs taken in pairs suggest the tangles descending
from the Dehn surgery realization of the Dehn twists on the trefoil.
Below we plug the above tangle with three different rational tangles.
Then we perform isotopies to obtain two-bridge presentations of the
resulting links. In this manner we may observe how the exterior of
K
admits the three cyclic fillings
S^3,
L(18,5), and
L(19,7).