Series

Resch — the series

6 essays on one idea, from the one that introduces it to the one that assumes the rest.
  1. what the construction produced23 twists, 122 interior verticesturned 24.1° from the tiling's edgespleats 0.068 to 0.068 wide1.58× smaller once the pleats are taken upevery vertex passes all four conditionsmountainvalleyraw edge

    Where two twists share a pleat

    Every twist tessellation the tradition draws has one size of twist, because every tiling it is drawn on has one kind of vertex. Hand the construction a tiling with two, and the pleat between a large twist and a small one turns out to fix their sizes exactly — three to one, and nothing else folds.

    part 1 · tessellation
  2. the equation on an edge, at both of its endsas drawnevery vertex moved 12 per centratio − 1round a loopratio − 1round a loopthe square grid000.200.90the triangular grid000.170.75the honeycomb000.351.73the rhombille tiling2.0002.992.14the elongated triangular tiling000.171.27the rhombille's tiles are not regular, its ratios are three and a third, and they still multiply to one

    The propagation that never had to work

    The twist construction carries one equation per edge of its tiling and propagates the twist sizes outward from a seed. On every tiling anybody has drawn a twist on, every one of those equations is satisfied trivially — both ends of an edge read the same two numbers, because a regular polygon has one interior angle. The construction has been running and doing nothing, and the one tiling where it did something is the one whose tiles are not regular.

    part 2 · tessellation
  3. do the pleat equations close round every loop, as drawn and under three linear mapstrivially means every edge's equation is one at both ends; otherwise the largest disagreement round a loopas drawnshearedstretchedgeneralthe square gridcloses, triviallycloses, triviallycloses, triviallycloses, triviallythe triangular gridcloses, triviallycloses, triviallycloses, triviallycloses, triviallythe honeycombcloses, triviallycloses, triviallycloses, triviallycloses, triviallythe rhombille tilingclosesoff by 1.76off by 2.18off by 2.96the elongated triangular tilingcloses, triviallyoff by 3.14closes, triviallyoff by 4.77the maps: a shear of 0.3, a stretch of 1.5 along one axis, and the matrix [1.3, 0.4; −0.2, 0.9]

    Closing the loops is not folding

    The twist construction propagates one equation along every edge of a tiling, and it can only work where the equations agree round every loop. Asked which irregular tilings pass, a linear map gives a clean answer: the square grid, the triangular grid and the honeycomb pass under every shear and stretch tried, because each edge has a half-turn symmetry that makes its equation exactly one at both ends, and a half-turn survives any linear map. The rhombille passes only as drawn. But passing is not folding. On every one of those images — including the ones whose loops close exactly — the construction produces a pattern that fails the angle condition at every turn tried. The loops were a necessary condition all along, and the construction needs something the tilings' images do not give it.

    part 3 · tessellation
  4. does the construction fold, with one side distance a vertex and with one a sideat a turn of 0.42 radians; the second construction's pleats run at -0.5 radians from their own edgesas drawnshearedstretchedgeneralone a vertex / one a sidethe square gridfolds/foldsno/foldsno/foldsno/foldsthe triangular gridfolds/foldsno/foldsno/foldsno/foldsthe honeycombfolds/foldsno/foldsno/foldsno/foldsthe rhombille tilingfolds/foldsno/foldsno/foldsno/foldsthe elongated triangular tilingfolds/foldsno/foldsno/foldsno/foldsthe maps: a shear of 0.3, a stretch of 1.5 along one axis, and the matrix [1.3, 0.4; −0.2, 0.9]

    One number where the corners wanted four

    The twist construction gives a vertex a single side distance, and every account of these patterns does the same — it is what rotate-and-shrink means. The conditions never asked for it. Written out, the corner condition is one linear equation per pleat crease in the distances taken one per edge, so a degree-four vertex carries four unknowns against two independent equations. Given them back, the twelve sheared and stretched tilings that refused to fold all fold.

    part 4 · tessellation
  5. each side of the twist, divided by the edge it facesone vertex of the the square grid under [1.3, 0.4, -0.2, 0.9]1.0520.3871.0520.387the weightsthe same edges, scaled by them, end to endthe 4 weighted edges close to 3e-16 of their own total length, and the two ends of every edge agree to 3e-15

    Every twist writes an equilibrium

    Divide each side of a twist polygon by the length of the edge it faces. The polygon closing says those numbers, weighted onto the edges, balance at the vertex; the pleat matching says the two ends of an edge agree on the number. Together they are a positive equilibrium stress — the thing a tiling has when it is the plan of a spider web — and the construction has been writing one at every vertex without being asked for it.

    part 5 · tessellation
  6. how much more the folded sheet draws in one way than the otherthe ratio of the two principal factors of the collapse, fitted to the twists' positions before and after foldingas drawnshearedstretchedgeneralthe square grid1.00004.41391.00003.5417the triangular grid1.00001.00001.00001.0000the honeycomb1.00002.81795.38555.0597the rhombille tiling1.00002.81795.38555.0597the elongated triangular tiling1.00004.41391.00003.5417one is a similarity — the folded sheet is the flat one scaled and turned, with no direction preferred

    The sheet draws in crooked

    Every twist tessellation measured here has collapsed by a similarity: the folded sheet is the flat one scaled and turned, the same way in every direction. The patterns that exist on sheared and stretched tilings do not. Ten of the fifteen images fold by a map with two different principal factors, up to five and a third to one — and the prediction that said which ten, made from the weights the pattern writes on its edges, is wrong in both directions.

    part 6 · tessellation

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