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Essays arrive in groups rather than one at a time. The most recent group is below in full, and every earlier one after it, newest first.

Essays arrive in groups rather than one at a time, and a group usually opens up a subject not covered before. Between one group and the next nothing changes, so a reader who has seen the most recent group has seen everything.

5 November 2026

5 essays on designing a base, folding nobody designed, who found it, and when, tessellations and what it costs to know

one budget, one split, two sheets: the bill for the five featuresthe arch is any rectangle, the valley a square sheet with a margin on the shorter side0.6000.800100.2500.5000.7501share of the budget spent on the strips acrosspaper over the original sheetany rectanglesquare sheeta shared budget of 0.100 of the sheet Designing a base

The split that is worst on a rectangle

Two families of grafted strips share an allowance of shortfall, and the bill is a product of two sides whose sum the allowance fixes. So where the allowance goes is a question about a rectangle with a set perimeter: its area is largest when level and smallest when lopsided. On a sheet that may be any rectangle the split that levels the sides is the dearest there is, and it is barely dearer, because the gap enters squared. On a square sheet the same split is the cheapest, and the gap enters to first order, ninety-four times as heavily on five features. On a grid the first answer dissolves — the strip nearest a line decides, not the family — and the second does not.

7 figures
a vertex held at its exact mirror imagesectors 60°, 90°, 120°, 90°, creased to a drive of 1.6 rad, with the rest angles relaxing toward the held angles0510152001234time held, in relaxation timesenergy in the springsthe flat sheetthe creased statethe held state Folding nobody designed

A crease held the other way

Hold a creased sheet on the far side of flat and its memory crosses zero after τ ln(1 + φ₀⁄φₕ), a time that contains no stiffness and no fold count. Asking what happens at that moment shows that two accounts of a corrugation's energy cannot both stand: a hinge whose memory can cross zero gives one parabola and no barrier at all. The barrier belongs to a degree-four vertex, whose two branches turn out to be at right angles in the space of its fold angles. Held on the other branch its wall dips and never falls, and its two resting states trade depth at nearly the same logarithm, with lengths in place of angles. Only the exact mirror takes every rest angle through zero together, which is the fastest way to erase a crease and the least forgiving.

7 figures
the recipe each family needs, before and after the layers are counteda parity is what must add up; a prohibition is what must not all agree; closed means a same-and-differ recipe can existrules asked aboutrulesparitiesprohibitionsclosedthe Yoshimura, at the vertices2612nothe Yoshimura, with a stacking2214nothe waterbomb, at the vertices3232nothe waterbomb, with a stacking1650yes Who found it, and when

Half the waterbomb's rules have no stack

The recipes for the waterbomb and the Yoshimura were written for the repeating rules that pass the vertex conditions, and nobody had asked those rules for a folded state. Asked, sixteen of the waterbomb's thirty-two have none, and four of the Yoshimura's twenty-six. Four panels are enough to refuse a waterbomb rule, in five lines, by forcing two creases on one folded line to interleave. And the waterbomb's surviving rules turn out to be exactly what a recipe of its kind was proved unable to describe: five same-and-differ clauses and no prohibition. Counting the layers shortens the waterbomb's recipe and lengthens the Yoshimura's, whose refusals are not local at all.

6 figures
where the usual Yoshimura lettering puts its panels, foldedevery course one letter, every zigzag the other; 4 by 4; panels drawn at their folded places Tessellations

The Yoshimura folds flat at a few heights

The Yoshimura's row height has always been treated as a free dial below the equilateral: the sectors close, the counts hold, the lemma has nothing to forbid. Asked for an actual stack of layers, its usual lettering refuses nearly everywhere. Folded, its triangles turn round one centre by twice the base angle at each step, and they close on a ring only when that angle is π over a whole number: a triangle at sixty degrees, a square at forty-five, a pentagon at thirty-six. At any other height the rosette spirals, and seven panels are enough to prove it cannot pass itself. Below π over the number of rows plus two, it does not get far enough round to meet itself, so the small patch hides this too.

6 figures
what finding a stacking costs at each height, on 4 by 4steps of the search, on a scale of powers of ten; dots mark the whole values of n, where the rosette closes2345634567n, where the base angle is π over nsteps, as a power of tenthe usual letteringzigzags split by bandzigzags split by lean What it costs to know

The proportion everyone draws is the hard one

The Yoshimura is drawn equilateral, and every cost and count of it has been measured there. Moved a quarter of a step along its own height dial, a search for a stacking that took 268,650 steps takes 808, and a sheet with 9,790 folded states has 92. The equilateral pattern is the most expensive member of its family on every sheet measured, because exact coincidence removes the conditions that a panel lying across a crease would impose: from 1,024 conditions to none. A drawing chosen for being easy to construct is the one instance where almost nothing constrains the layers, and a population of one chosen drawing had been reporting that freedom as the difficulty of the pattern.

6 figures

Before that

Everything published earlier, newest first. Titles only — the cards are on the full listing.

3 November 2026

3 essays on who found it, and when, what it costs to know and rigid folding

30 October 2026

3 essays on tessellations, designing a base and axioms and construction

23 October 2026

3 essays on what it costs to know, curves and material and folding nobody designed

21 October 2026

4 essays on who found it, and when, curves and material, rigid folding and tessellations

19 October 2026

5 essays on rigid folding, tessellations, designing a base, folding nobody designed and axioms and construction

14 October 2026

7 essays on rigid folding, axioms and construction, designing a base, folding nobody designed, who found it, and when, what it costs to know and curves and material

5 October 2026

4 essays on folding nobody designed, who found it, and when, what it costs to know and curves and material

2 October 2026

4 essays on tessellations, designing a base and axioms and construction

30 September 2026

6 essays on who found it, and when, curves and material, folding nobody designed, designing a base, rigid folding and what it costs to know

27 September 2026

6 essays on curves and material, tessellations, designing a base, axioms and construction, folding nobody designed and rigid folding

26 September 2026

8 essays on what it costs to know, axioms and construction, designing a base, who found it, and when, curves and material, rigid folding, tessellations and folding nobody designed

25 September 2026

7 essays on curves and material, tessellations, rigid folding, designing a base, axioms and construction, who found it, and when and what it costs to know

24 September 2026

8 essays on designing a base, tessellations, curves and material, rigid folding, axioms and construction, who found it, and when, folding nobody designed and what it costs to know

23 September 2026

8 essays on axioms and construction, designing a base, who found it, and when, rigid folding, folding nobody designed and what it costs to know

19 September 2026

12 essays on tessellations, curves and material, folding nobody designed, what it costs to know and rigid folding

16 September 2026

32 essays on folding nobody designed, what it costs to know, axioms and construction, designing a base, who found it, and when, curves and material, rigid folding and tessellations

15 September 2026

20 essays on folding nobody designed, axioms and construction, designing a base, who found it, and when, curves and material and rigid folding

13 September 2026

9 essays on who found it, and when, folding nobody designed, rigid folding, axioms and construction and curves and material

12 September 2026

15 essays on folding nobody designed, who found it, and when, curves and material, rigid folding, axioms and construction and designing a base

10 September 2026

20 essays on folding nobody designed, axioms and construction and who found it, and when

5 September 2026

50 essays on flat-folding, tessellations, what it costs to know, curves and material, designing a base, rigid folding, axioms and construction, who found it, and when and folding nobody designed

3 September 2026

20 essays on what it costs to know, flat-folding, tessellations, designing a base, curves and material, rigid folding, who found it, and when and folding nobody designed

1 September 2026

20 essays on flat-folding, what it costs to know, tessellations, curves and material, rigid folding, designing a base, folding nobody designed and who found it, and when

31 August 2026

20 essays on flat-folding, tessellations, what it costs to know, curves and material, axioms and construction, who found it, and when, rigid folding, designing a base and folding nobody designed

30 August 2026

20 essays on flat-folding, tessellations, what it costs to know, curves and material, rigid folding, designing a base, axioms and construction, who found it, and when and folding nobody designed

29 August 2026

20 essays on flat-folding, tessellations, rigid folding, designing a base, what it costs to know, curves and material, axioms and construction, who found it, and when and folding nobody designed

27 August 2026

15 essays on flat-folding, tessellations, curves and material, designing a base, what it costs to know, folding nobody designed, rigid folding, axioms and construction and who found it, and when

26 August 2026

15 essays on flat-folding, rigid folding, designing a base, what it costs to know, curves and material, tessellations, axioms and construction, who found it, and when and folding nobody designed

24 August 2026

15 essays on flat-folding, rigid folding, designing a base, tessellations, curves and material, what it costs to know, axioms and construction, who found it, and when and folding nobody designed

22 August 2026

15 essays on flat-folding, rigid folding, tessellations, designing a base, curves and material, axioms and construction, what it costs to know and who found it, and when

21 August 2026

15 essays on flat-folding, rigid folding, tessellations, designing a base, curves and material, axioms and construction and what it costs to know

20 August 2026

15 essays on flat-folding, curves and material, rigid folding, designing a base, tessellations, axioms and construction and what it costs to know

19 August 2026

15 essays on tessellations, curves and material, designing a base, what it costs to know, flat-folding, axioms and construction and rigid folding

17 August 2026

15 essays on flat-folding, curves and material, rigid folding, axioms and construction, designing a base and tessellations

16 August 2026

15 essays on flat-folding, designing a base, rigid folding, tessellations, axioms and construction and curves and material

14 August 2026

15 essays on folding nobody designed

13 August 2026

15 essays on who found it, and when

11 August 2026

15 essays on what it costs to know, axioms and construction, tessellations, designing a base and curves and material

10 August 2026

12 essays on flat-folding, what it costs to know, designing a base, axioms and construction, tessellations, rigid folding and curves and material

7 August 2026

15 essays on tessellations, rigid folding and curves and material

3 August 2026

19 essays on axioms and construction, flat-folding, designing a base and tessellations

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