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Questions tagged [knot-link]

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50 votes
2 answers
2k views

Can I wrap a suitcase with hair ties

Is there a nontrivial link in a big solid torus that is trivial in the ambient Euclidean space such that each circle is unknot and has a sufficiently small length? It is motivated by a question that ...
Anton Petrunin's user avatar
17 votes
2 answers
406 views

Random rings linked into one component?

Let $S$ be a sphere of unit radius. Let $C_n$ be a collection of unit-radius circles/rings whose centers are (uniformly distributed) random points in $S$, and which are oriented (tilted) randomly (...
Joseph O'Rourke's user avatar
9 votes
1 answer
587 views

How to prove the product of Whitehead manifold and $\mathbb{R}$ is homeomorphic to $\mathbb{R}^4$?

I am currently reading Rolfsen's "Knots and Links". At page 82 Whitehead manifold $W$ is defined and an exercise asking to show that $W\times \mathbb{R}\cong \mathbb{R}^4$ is left. Reference ...
Math Diego's user avatar
10 votes
2 answers
598 views

Is there a "simplest" way to embed a graph in 3-space?

I consider embeddings of graphs into 3-space with edges embedded as arbitrary curves. In the simplest (non-trivial) case the graph $G$ is a cycle or union of cycles, in which case the embeddings can ...
M. Winter's user avatar
  • 13.6k
10 votes
2 answers
388 views

Tangled random triangles: One giant component?

Suppose you have $n$ triangles whose corners are random points on a sphere $S$ in $\mathbb{R}^3$. Viewing the triangles as built from rigid bars as edges, two triangles are linked if they cannot be ...
Joseph O'Rourke's user avatar
4 votes
1 answer
262 views

Infinitely many Brunnian links with bounded crossings

A set of Brunnian link is a nontrivial link such that if one component is removed, it becomes trivial. The best known example is the Borromean rings: Here's a six component example: There is likely ...
Christopher King's user avatar
2 votes
1 answer
222 views

Link invariants distinguishing components

I was recently thinking about links where each component plays the same role: for every permutation of components, there is an isotopy permuting these components in the prescribed way. In the vein of ...
Nikhil Sahoo's user avatar
  • 1,225