منابع مشابه
Levelling an unknotting tunnel
It is a consequence of theorems of Gordon–Reid [4] and Thompson [8] that a tunnel number one knot, if put in thin position, will also be in bridge position. We show that in such a thin presentation, the tunnel can be made level so that it lies in a level sphere. This settles a question raised by Morimoto [6], who showed that the (now known) classification of unknotting tunnels for 2–bridge knot...
متن کاملUnknotting Unknots
A knot is an embedding of a circle into three-dimensional space. We say that a knot is unknotted if there is an ambient isotopy of the embedding to a standard circle. In essence, an unknot is a knot that may be deformed to a standard circle without passing through itself. By representing knots via planar diagrams, we discuss the problem of unknotting a knot diagram when we know that it is unkno...
متن کاملUnknotting Genus One Knots
There is no known algorithm for determining whether a knot has unknotting number one, practical or otherwise. Indeed, there are many explicit knots (11328 for example) that are conjectured to have unknotting number two, but for which no proof of this fact is currently available. For many years, the knot 810 was in this class, but a celebrated application of Heegaard Floer homology by Ozsváth an...
متن کاملA technique for unknotting an intracardiac flow-directed balloon catheter.
Described is an unusual complication occurring during right-sided cardiac catheterization using a 7F flow-directed balloon catheter. During an attempt to direct the catheter from the main pulmonary artery into the pulmonary wedge position, the tip became entangled in a loop of catheter and knotted. Initially, all attempts to unknot or remove the catheter failed. A movable core guide wire was pa...
متن کاملUnknotting number and knot diagram
TImis note is a continuation of [Nl], Wbere we have discusged tbe unknotting number of knots With rspect tía knot diagrams. Wc wilI show that for every minimum-crossing knot-diagram among ah unknotting-number-one two-bridge knot there exist crossings whose exchangeyields tIme trivial knot, ib tbe tbird Tait conjecture is true.
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ژورنال
عنوان ژورنال: Journal of Pure and Applied Algebra
سال: 1975
ISSN: 0022-4049
DOI: 10.1016/0022-4049(75)90025-0