The Series
All 20 Puzzles
Ordered for learning, not difficulty alone. Numbers are display positions; the five arcs build on one another.
1
The Gatekeeper
Unknot recognition ▶ Open in explorer #1
2
Shepherd's Yoke
Buttonhole homotopy ▶ Open in explorer #2
3
The Prisoner's Ring
Linking number cancellation ▶ Open in explorer #3
4
Mobius Snare
Non-orientability (Mobius boundary) ▶ Open in explorer #4
5
The Mirror Gate
Chirality (handedness) ▶ Open in explorer #5
6
Trinity Lock
Borromean rings (no pairwise linking) ▶ Open in explorer #6
7
Devil's Pitchfork
Fundamental group of configuration space ▶ Open in explorer #7
8
The Ferryman's Knot
Open knot vs. closed knot; Reidemeister moves on constrained arcs ▶ Open in explorer #8
9
The Crossing Number
Unknotting number (crossing changes) ▶ Open in explorer #9
13
The Braid Cage
Braid groups (Yang-Baxter relation) ▶ Open in explorer #13
14
The Torus Winder
Torus knots — (p,q) winding numbers ▶ Open in explorer #14
15
The Tricolor Lock
Fox tricolorability (knot invariant) ▶ Open in explorer #15
16
The Seifert Sail
Seifert surfaces (surfaces bounded by knots) ▶ Open in explorer #16
17
The Satellite Trap
Satellite knots (JSJ decomposition) ▶ Open in explorer #17
18
The Whitehead Waltz
Whitehead link — linking number zero without splittability ▶ Open in explorer #18
19
The Tangle Dance
Conway rational tangles — the fraction is a complete invariant ▶ Open in explorer #19
20