Alternating Knot
An alternating knot is a Knot which possesses a knot diagram in which crossings alternate between under- andoverpasses. Not all knot diagrams of alternating knots need be alternating diagrams.
The Trefoil Knot and Figure-of-Eight Knot are alternating knots. One of Tait's Knot Conjecturesstates that the number of crossings is the same for any diagram of a reduced alternating knot. Furthermore, a reducedalternating projection of a knot has the least number of crossings for any projection of that knot. Both of these factswere proved true by Kauffman (1988), Thistlethwaite (1987), and Murasugi (1987).
If 
has a reduced alternating projection of 
crossings, then the Span of is 
. Let
be the Crossing Number. Then an alternating knot 
(aKnot Sum) satisfies
In fact, this is true as well for the larger class of Adequate Knots and postulated for all Knots.The number of Prime alternating knots of
crossing for 
, 2, ... are 0, 0, 1, 1, 2, 3, 7,18, 41, 123, 367, ... (Sloane's A002864).See also Adequate Knot, Almost Alternating Link, Alternating Link, Flyping Conjecture
References
Adams, C. C. The Knot Book: An Elementary Introduction to the Mathematical Theory of Knots. New York: W. H. Freeman, pp. 159-164, 1994. Arnold, B.; Au, M.; Candy, C.; Erdener, K.; Fan, J.; Flynn, R.; Muir, J.; Wu, D.; and Hoste, J. ``Tabulating Alternating Knots through 14 Crossings.'' ftp://chs.cusd.claremont.edu/pub/knot/paper.TeX.txt. Arnold, B.; Au, M.; Candy, C.; Erdener, K.; Fan, J.; Flynn, R.; Muir, J.; Wu, D.; and Hoste, J. ftp://chs.cusd.claremont.edu/pub/knot/AltKnots/. Erdener, K. and Flynn, R. ``Rolfsen's Table of all Alternating Diagrams through 9 Crossings.'' ftp://chs.cusd.claremont.edu/pub/knot/Rolfsen_table.final. Kauffman, L. ``New Invariants in the Theory of Knots.'' Amer. Math. Monthly 95, 195-242, 1988. Murasugi, K. ``Jones Polynomials and Classical Conjectures in Knot Theory.'' Topology 26, 297-307, 1987. Sloane, N. J. A. SequenceA002864/M0847in ``An On-Line Version of the Encyclopedia of Integer Sequences.''http://www.research.att.com/~njas/sequences/eisonline.html and Sloane, N. J. A. and Plouffe, S.The Encyclopedia of Integer Sequences. San Diego: Academic Press, 1995. Thistlethwaite, M. ``A Spanning Tree Expansion for the Jones Polynomial.'' Topology 26, 297-309, 1987.
- Complete Permutation
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- Completing the Square
- Complex
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- Composite Knot