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Knotting Mathematics and Art University of Southern Florida, Nov.3, 2007. Carlo H. Séquin U.C. Berkeley. Knotty problems in knot theory. Naughty Knotty Sculptures. Sculptures Made from Knots (1). 2004 - 2007: Knots as constructive building blocks. Tetrahedral Trefoil Tangle (FDM).
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Knotting Mathematics and ArtUniversity of Southern Florida, Nov.3, 2007 Carlo H. Séquin U.C. Berkeley Knotty problems in knot theory • NaughtyKnotty Sculptures
Sculptures Made from Knots (1) • 2004 - 2007:Knots as constructive building blocks.
Tetra Trefoil Tangles • Simple linking (1) -- Complex linking (2) • {over-over-under-under} {over-under-over-under}
Tetra Trefoil Tangle (2) • Complex linking -- two different views
Tetra Trefoil Tangle • Complex linking (two views)
Octahedral Trefoil Tangle (1) • Simplest linking
Platonic Trefoil Tangles • Take a Platonic polyhedron made from triangles, • Add a trefoil knot on every face, • Link with neighboring knots across shared edges. • Tetrahedron, Octahedron, ... done !
Icosahedral Trefoil Tangle • Simplest linking (type 1)
Icosahedral Trefoil Tangle(type 3) • Doubly linked with each neighbor
Realization: Extrude Hone - ProMetal • Metal sintering and infiltration process
Sculptures Made from Knots (2) For this conference I have been looking for sculptures where the whole piece is just a single knot and which also involve some “interesting” knots. • Generate knots & increase their complexity in a structured, procedural way: • I. Bottom-up assembly of knots • II. Top-down mesh infilling • III. Longitudinal knot splitting • Make aesthetically pleasing artifacts
Outline • I.Bottom-up assembly of knots • II.Top-down mesh infilling • III. Longitudinal knot splitting
The 2D Hilbert Curve (1891) • A plane-filling Peano curve Do This In 3 D !
“Hilbert” Curve in 3D Replaces an “elbow” • Start with Hamiltonian path on cube edges and recurse ...
Jane Yen: “Hilbert Radiator Pipe” (2000) • Flaws( from a sculptor’s . point of view ): • 4 coplanar segments • Not a closed loop • Broken symmetry
A Knot Theorist’s View Thus our construction element should use a “more knotted thing”: e.g. an overhand knot: It is still just the un-knot !
Recursion Step • Replace every 90° turn with a knotted elbow.
Also: Start from a True Knot • e.g., a “cubist” trefoil knot.
A Knot Theorist’s View Thus our assembly step should cause a more serious entanglement: Perhaps knotting together crossing strands . . . • This is just a compound-knot ! • It does not really lead to a complex knot !
Recursive 9-Crossing Knot 9 crossings • Is this really a 81-crossing knot ?
From Paintings to Sculptures • Do something like this in 3D ! • Perhaps using two knotted strands(like your shoe laces).
Frank Smullin (1943 – 1983) • Tubular sculptures; • Apple II program for • calculating intersections.
Frank Smullin (Nashville, 1981): Granny Knot Square Knot • “ The Granny-knot has more artistic merits than the square knot because it is more 3D;its ends stick out in tetrahedral fashion... ”
Granny Knot as a Building Block Smullin: “TetraGranny” • Four tetrahedral links, like a carbon atom ... • can be assembled into diamond-lattice ... ... leads to the “Granny-Knot-Lattice”
A “Knotty” “3D” Recursion Step • Use the Granny knot as a replacement element where two strands cross ...
Next Recursion Step • Substitute the 8 crossings with 8 Granny-knots
One More Recursion Step Too much complexity ! • Now use eight of these composite elements; • connect; • beautify.
A Nice Symmetrical Starting Knot • Granny Knot with cross-connected ends 4-fold symmetric Knot 819
Recursion Step • Placement of the 8 substitution knots
Establishing Connectivity • Grow knots until they almost touch
Work in Progress ... • Connectors added to close the knot
Outline • I.Bottom-up assembly of knots • II.Top-down mesh infilling • III. Longitudinal knot splitting
Recursive Figure-8 Knot Result after 2 more recursion steps Mark crossings over/under to form alternating knot • Recursion step
Recursive Figure-8 Knot • Scale stroke-width proportional to recursive reduction
2.5D Recursive (Fractal) Knot Trefoil Recursion • Robert Fathauer: “Recursive Trefoil Knot”
Recursion on a 7-crossing Knot ... Map “the whole thing” into all meshes of similar shape • Robert Fathauer, Bridges Conference, 2007
From 2D Drawings to 3D Sculpture • Too flat ! Switch plane orientations