One step of the grid, again
Worth reading first: The organ that was taken away · Where a handover sits.
A search of the fine end of both branches went looking for a lattice whose wrecked cuts keep a lag outside the four the census holds. It found one: the Lucas branch at a rise of 0.006, on the 7/11 rung, three of whose offsets keep a lag of 11.
The search stepped from 0.0070 to 0.0060 in one move. At the coarser rise every cut that wrecks keeps 7; at the finer, three keep 11. So the change is somewhere inside a hundred steps of the grid the ladder names its rises on, and nothing said where.
The design
Two grids, the second only where the first says something happened.
The coarse pass cuts the nine intermediate rises of the ten-thousandth grid — 0.0069 down to 0.0061 — plus the two ends the search already has, so this table contains the rows it is a refinement of rather than being a rival reading of them.
The fine pass takes every adjacent pair whose answer differs and cuts all nine interior rises of the hundred-thousandth grid between them. That is the grid the ladder itself is named on, and it is where a slot was found to lose its second wall inside one step.
Why refine every bracket rather than bisect
A bisection assumes the answer changes once and monotonically, and neither is known in advance. The golden 8/13 band changes back and forth nineteen times, so an assumption of monotonicity on a quantity of this kind has been refuted on the object next door.
Refining every bracket costs more when there are several and the same when there is one. A budget caps the total, and a bracket left unrefined is reported as unrefined rather than dropped.
In the event there was one bracket, so the two designs would have agreed — which is not a reason to have chosen the weaker one.
What it cost
Twenty rises, eighty-nine cut stems, two hundred and eighty stems in all counting the controls, and about seven minutes.
That is cheap because a rise here is thirteen offsets tried and about four wrecking, rather than a band’s worth. The expense in this thread is bands: 1,120 to 1,890 cut stems each.
The comparison is worth making because the two designs answer different questions. A band holds the lattice still and moves the rise a little; this moves the rise across nearly a sixth of a rung and lets everything move with it.
The answer
Between h = 0.00640 and h = 0.00639. One step of the grid.
Above it, at every one of the eight rises from 0.0070 down, every wrecking cut keeps 7 and none keeps 11. Below it, at every one of the eleven rises down to 0.0060, some cut keeps 11.
So it is a transition and not a stretch where both occur. There is no rise in the search at which the answer is ambiguous, none at which it changes back, and no interval over which the two families alternate.
Which is the second such transition
The first is the slot that loses its second wall, on the golden 5/8 rung, located between 0.00998 and 0.00997 — also one step of the same grid, also with nothing continuous changing across it.
Two transitions on two rungs of two branches, both one part in a thousand of the rise wide, both in quantities that are integers or discrete states read off a run. That is a pattern worth naming even at two cases: the discrete readings in this thread change sharply, and the sweeps that have looked have found no gradual case.
What would refute it is a quantity of the same kind that changes over ten grid steps rather than one. Nothing has produced one.
And nothing about the lattice moves across it
This is the check that makes a transition a transition rather than a lattice change.
The settled divergence is 99.2578 degrees on both sides, to every digit the azimuth grid carries — the grid is 1,536 samples of the circle, a quarter of a degree a step, and the two readings are identical rather than close. The counted pair is 7/11 on both sides.
The ordering of the two contact hops is the same on both sides: the 11-hop is shorter at both rises, as it is at every rise from 0.008 down. Their lengths change by about a part in a thousand across the step, in the direction they were already moving.
So what changes is which cuts wreck
At 0.00640 the offsets that wreck are 5, 6 and 7, and all three keep 7. At 0.00639 they are 5, 6, 7 and 9, and the new one keeps 11.
Nothing changes its mind. An offset that was wrecking and keeping 7 goes on wrecking and keeping 7; an offset that was recovering starts wrecking, and what it keeps is the family the search was looking for.
That is a different shape from the one the question assumed. The rise this search locates is the rise at which the lattice first keeps 11 anywhere, and it is located by an arrival rather than by a change of answer.
Which offsets wreck, again
The wrecking set moves from rise to rise across the whole search, exactly as it does across every band cut whole.
At 0.0070 it is {4, 5, 7}. At 0.0069 it is {5, 6, 7}. At 0.0068 it is {5, 7, 8}. At 0.0067 it is {5, 7}. At 0.0066 it is {5, 6, 7} again. At 0.0065 it is {5, 6, 7, 8}.
Six consecutive rises, six membership changes, one part in a hundred and forty apart in the rise. The band sweeps found the same thing over stretches of rise; here it is visible between adjacent readings.
What that does to a census
A census cuts every offset at a chosen rise and reports what it finds. The offsets that wreck at that rise are its rows.
On this stretch, a census taken at 0.0067 has two rows and one taken at 0.0060 has six. Neither is wrong. They are censuses of different sizes because the rise decides membership, and the rise was chosen for coverage rather than for membership.
That is the same boundary the third band put round the same claims, and it is worth repeating because the ablation census’s ten lattices are the base of most of this thread.
The eleven-keeping set fills in
Below the transition the offsets keeping 11 grow: {9} at 0.00639 and 0.00638, {8, 9} at 0.00637, {9, 10} at 0.00636, {8, 9} again for four rises, then {8, 9, 10} from 0.00631 down to 0.0060.
So the arrival is not a single event but a stretch over which more offsets join. The located rise is where the first one does, and that is the quantity the fine-end search was asking about.
By 0.0060 — the rise the search actually cut and the one the exchange’s fifth hop cluster comes from — three offsets keep 11 and three keep 7, which is the row the census gained.
Offset 8 is the one that changes its mind
And it cannot be located. It wrecks at 0.0068 keeping 7, at 0.0065 keeping 7, and at 0.00637 keeping 11 — and it does not wreck at 0.0064, 0.00639 or 0.00638.
So its own change is bracketed across thirteen steps of the grid, and the bracket contains the transition without that meaning anything. It is the same limit the third band ran into: an offset’s answer exists only where its cut wrecks, and the wrecking set moves faster than the answer does.
Two sweeps, two questions, one limit. Naming it in both places is the point, because it is structural rather than a matter of resolution.
What a rung buys that a band does not
A band holds the settled divergence still to within a twentieth of a degree, which is what makes it the right object for asking whether the survivor changes with nothing else moving.
A rung is looser. Across this stretch the divergence moves from 99.141 to 99.344 degrees — two tenths, four times a band’s tolerance — so a change anywhere in it could in principle be a change in the lattice.
What makes the located transition safe is that the divergence is held across the step rather than across the stretch. The two rises either side read identically, so whatever the divergence is doing over the search as a whole, it is doing nothing there.
The refusal
A search whose two ends agree has nothing to bracket, and the reading must say so rather than reporting a transition between the only two rises it looked at.
That is checked by asking for a stretch at the coarse end of the same rung, one grid step wide, where every cut keeps 7 on both sides. It opens no bracket and spends no fine cuts, which is the answer it must give.
The check costs two rises rather than a rung, which is the same economy a refusal on a band was rewritten for after one provoked its refusal by cutting seventy rises to learn one boolean.
Why this rung and not another
Because it is the only rung on the ladder whose cuts have ever kept a lag of 11, and the reason is arithmetic rather than luck. A surviving family is a contact family of the lattice, so a lag of 11 needs a counted pair with an 11 in it, and on the two branches those are the golden 8/13 rung and the Lucas 7/11.
The golden half has no object at all. Every golden rise inside the 8/13 rung keeps 8 or 4, and at not one of them does the cut leave the longer of the two counted steps standing — the 13 is there and is never what survives.
So the whole question lives on one rung of one branch, and this search is the whole of what can be asked about it without leaving the ladder.
What the transition is not
It is not the two contact steps changing places. That happens on this rung too — it is what makes it a rung with a handover — and it happens at 0.00804, a hundred and sixty-four grid steps higher.
It is not the counted pair changing. The pair is 7/11 from 0.00947 down to 0.00570, which is the whole rung, and the transition sits comfortably inside.
And it is not the stem leaving its branch. The settled divergence is within four tenths of a degree of the Lucas angle at every rise of the search, where the rises below the ladder’s finest rung sit thirty to eighty-eight degrees off it.
The window the answer is read through
A surviving family is the smallest lag whose hop the wrecked run holds rigid, read over a window at the top of the run. That window is a hundred and twenty organs, and it is one of the instrument settings this collection has learned to distrust.
It matters less here than elsewhere. The reading is a boolean per lag — held or not held — and across the census the rigid lags hold their angle to within a fraction of a degree while the others miss by tens, so the verdict is a separation rather than a threshold.
Where the window does bite is on a survivor large enough that a hundred and twenty organs gives few repeats of it. At a lag of 11 that is eleven samples a class, which is comfortable; at a lag of 20 it is six and the reading has to be declined.
What a hundred grid steps hid
The fine-end search that produced this question is a search rather than a sweep, and it says so: ten rises a branch, chosen to cover the two rungs where an 11 could appear and to run down past the ladder’s finest rise.
Its step is not a resolution. Between 0.0070 and 0.0060 it takes one step, which is a hundred rises of the grid the ladder is named on, and between 0.0040 and 0.0035 it takes one step of fifty. A search designed to answer does this exist anywhere is under no obligation to be uniform.
What it cannot do is locate anything, and this round is the price of that: the search answered its own question in eight minutes and left a hundred-step bracket that costs seven more to close.
What would be different one rung up
Nothing that can be tested, because the 4/7 rung has no 11 in its pair and no cut on it can keep one. The question does not exist there.
That is worth saying because it bounds the generality of everything here. This is one transition, on one rung, in one quantity, and there is no second instance of it available on this ladder — not because nobody has looked but because the arithmetic forbids one.
A second instance would need a different ladder: a different falloff exponent, or a different geometry, either of which changes the rungs and the pairs they carry. That is a different question rather than a replication of this one.
What the seven minutes bought
A rise located to one part in a hundred thousand, with the lattice held across it, on a quantity that had been known to a hundred grid steps.
That is a good return for eighty-nine cut stems, and it is worth comparing against the two alternatives. A blind sweep of the whole rung at the same grid is 378 rises of cutting, about two hours, and would locate the same rise no better. A finer version of the fine-end search — twenty rises a branch instead of ten — would have halved the bracket and cost as much as this did, without closing it.
The design that works is: search coarsely for existence, then refine inside whatever bracket the search leaves. It is the same shape as the three sweeps that located a slot losing a wall, and it works for the same reason — the quantity changes once, so the bracket is real.
What would have made it fail
A quantity that changes back. Nothing in advance ruled that out: the golden 8/13 band changes nineteen times across 126 rises, so a survivor that alternates was the shape most recently observed on a neighbouring object.
The design handles it — every bracket is refined, not just the first — and it cost nothing here because there was one bracket. Had there been three, the fine pass would have spent twenty-seven rises instead of nine and reported three located changes.
That is the difference between a design that assumes an answer and one that admits it. The budget is what stops the second from being unbounded, and a bracket left unrefined is reported as unrefined rather than dropped.
What the twenty rises hold besides the answer
A record of the wrecking set across a sixth of a rung at the finest resolution anybody has taken it. Seven consecutive rises give seven different sets of wrecking offsets, and that is the same instability the band sweeps found over stretches of rise — here between neighbours.
It also holds the survivors at every one of those rises, which is what makes the located transition a statement about the lattice rather than about one cut: the answer is read from four to six offsets at each rise, not from one.
Neither was the point of the search, and both come out of it for nothing, because the sweep returns everything it measured rather than the summary the question needed.
What is claimed
That on the Lucas 7/11 rung the family a wrecking cut leaves standing first includes 11 between two rises one hundred-thousandth apart; that no rise above keeps it and every rise below does; and that the counted pair, the settled divergence and the ordering of the two contact hops are identical on both sides.
That the change is an offset arriving rather than an offset changing its answer, and that the one offset which does change its answer is not locatable at this resolution.
And that this is the second discrete transition in the thread located to one step of the grid the ladder is named on, with nothing continuous moving across either.
What links here
Computed from the collection, not written here: the essays that point at this one.
Shares its objects with
Essays that name at least two of the same things, and that neither author linked.
- A band with nothing inside it — both name ablation, claim testing, contact family, honest limits, resolution, rung
- Nine rises were not enough — both name census design, claim testing, contact family, discretisation, honest limits, resolution
- The alternation is not a period — both name ablation, claim testing, honest limits, resolution, rigid hop, rung
- The column nobody read — both name ablation, census design, claim testing, honest limits, resolution, rung
- The offsets that never change — both name ablation, claim testing, honest limits, resolution, rigid hop, rung
- Three offsets, three crossings — both name ablation, claim testing, honest limits, resolution, rigid hop, rung
Named objects
A flat tag is an object no other essay names yet.
AblationCensus designClaim testingContact familyDiscretisationHonest limitsHop lengthResolutionRigid hopRungSearchTransition