Stick number

Six is the lowest stick number for any nontrivial knot. There are few knots whose stick number can be determined exactly. Gyo Taek Jin determined the stick number of a (p, q)-torus knot T(p, q) in case the parameters p and q are not too far from each other (Jin 1997):

${\displaystyle {\text{stick}}(T(p,q))=2q{\text{, if }}2\leq p<q\leq 2p.\,}$

The same result was found independently around the same time by a research group around Colin Adams, but for a smaller range of parameters (Adams et al. 1997).

Square knot = trefoil + trefoil reflection.

Figure-eight knot, stick number 7

The stick number of a knot sum can be upper bounded by the stick numbers of the summands (Adams et al. 1997, Jin 1997):

${\displaystyle {\text{stick}}(K_{1}\#K_{2})\leq {\text{stick}}(K_{1})+{\text{stick}}(K_{2})-3\,}$

The stick number of a knot K is related to its crossing number c(K) by the following inequalities (Negami 1991, Calvo 2001, Huh & Oh 2011):

${\displaystyle {\frac {1}{2}}(7+{\sqrt {8\,{\text{c}}(K)+1}})\leq {\text{stick}}(K)\leq {\frac {3}{2}}(c(K)+1).}$

These inequalities are both tight for the trefoil knot, which has a crossing number of 3 and a stick number of 6.

• Weisstein, Eric W. "Stick number". MathWorld.
• "Stick numbers for minimal stick knots", KnotPlot Research and Development Site.