Simpler Brunnian "rubberband" loops?

  • Context: Undergrad 
  • Thread starter Thread starter egmoen
  • Start date Start date
  • Tags Tags
    Knot theory Loops
Click For Summary
SUMMARY

The discussion centers on simplifying Brunnian "rubberband" loops by using lark's-head (cow hitch) knots instead of the standard configuration, which requires 8 crossings. The proposed method reduces the crossings to 6 per pair and allows for a radial cut through the structure to sever only two bights. This approach maintains the Brunnian property, where removing any element causes the entire structure to fall apart. The author suggests the name "an exaltation of larks" for this new configuration, highlighting its novelty and potential for further exploration.

PREREQUISITES
  • Understanding of Brunnian links and their properties
  • Familiarity with knot theory and knot types
  • Knowledge of lark's-head (cow hitch) knots
  • Basic skills in visualizing and manipulating 3D structures
NEXT STEPS
  • Research the mathematical properties of Brunnian links
  • Explore knot construction tools like KnotPlot
  • Investigate the historical context and existing literature on rubberband knots
  • Experiment with creating and visualizing lark's-head knots in various configurations
USEFUL FOR

Mathematicians, knot theorists, and hobbyists interested in knot construction and the properties of Brunnian links will benefit from this discussion.

egmoen
Messages
3
Reaction score
1
TL;DR
Depictions of Brunnian "rubberband" loops show inividual elements being joined in a way that requires 8 crossings per pair; it seems like if we use lark's-head knots we reduce this to 6.
The standard configuration of Brunnian "rubberband" loops shows a series of unknots each bent into a U-shape, with their ends looped around the middle of the next unknot. (See for instance http://katlas.math.toronto.edu/wiki/"Rubberband"_Brunnian_Links). This connection requires 8 crossings.

If we connect the unknots together using a simpler lark's-head (cow hitch) knot, we still get a set of Brunnian links, since removing any element causes the entire structure to fall apart. But this is much simpler than the method shown above. It requires only 6 crossings per pair, and means that a radial cut through the overall structure only needs to sever two bights, not four. (A picture of a non-Brunnian chain using lark's-head knots can be found here: https://www.cs.bham.ac.uk/research/projects/cogaff/misc/rubber-bands.html)

Since I can't find an earlier description of this possibility, I'm worried that I have missed something that might disqualify this approach.
 
Physics news on Phys.org
Here's what I'm visualizing. If this works and doesn't have a name yet, it should definitely be called "an exaltation of larks", right?
exaltation.png
 
  • Like
Likes   Reactions: jim mcnamara
Yeah, I saw the katlas page...not much on there.

But would you agree that the loop above can't be separated without cutting an element, and falls apart if you cut any element?
 
So it seems. But as to being a unique Brunnian knot, I do not know. These constructs are sometimes called "rubberband" knots. Make one for yourself and play with it. Maybe one of the mathematicians here knows something more substantial.

@mathwonk @lavinia @fresh_42 seem like possibilities.

I think you may have already found https://www.knotplot.com/ which let's you play around with knot construction.
 

Similar threads

  • · Replies 26 ·
Replies
26
Views
5K
  • · Replies 7 ·
Replies
7
Views
3K
  • · Replies 24 ·
Replies
24
Views
6K
  • · Replies 9 ·
Replies
9
Views
4K
Replies
9
Views
6K
  • · Replies 13 ·
Replies
13
Views
10K
  • · Replies 2 ·
Replies
2
Views
10K