A band with nothing inside it
Worth reading first: Where a handover sits · The organ that was taken away.
The interesting picture on this ladder is the one with the speckle in it. One band cut at every rise came back with three offsets changing their answer inside it, in thirteen islands one to three rises wide whose gaps fit no period.
This essay is about the other one, and it is about the picture with nothing in it.
What is being reported
Five offsets wreck somewhere on the Lucas 7/11 band. Every one of them keeps the 7 family at every rise it wrecks at — 124 rises, 1,612 cut stems, and one answer.
That is a negative, and a negative is worth exactly what its resolution is worth. Stating the resolution is therefore most of the work: the sweep steps by two parts in a thousand in the rise, so a feature two rises wide is two parts in a thousand of the rise wherever on the band it sits, and there is not one.
The other band’s islands are one to three rises wide at that same step, which is what makes the comparison a comparison. A sweep whose resolution could not have resolved the thing it did not find would have reported the same picture and meant nothing by it.
Why a uniform picture is not obviously boring
The reason to expect something is that a band moves plenty. Across its 124 rises the rise itself changes by a factor of 1.16, the shorter of the two contact steps changes places with the longer one, and which offsets wreck at all changes on more than a tenth of its steps.
So the band is not a stretch where nothing happens. It is a stretch where three quantities are held on purpose — the counted pair, the settled divergence and, by construction, nothing else — and where a fourth was found to move on the other band. Here the fourth does not move while the rest of it does.
Five offsets, and they are not the same five
Offsets 4 through 8 wreck somewhere on this band. The set is not the same at every rise: offsets 5, 6 and 7 wreck at all 124, offset 8 wrecks at 88 of them and offset 4 at only 27.
That is the same phenomenon the golden band showed — which offsets wreck is a property of the lattice and the rise rather than of the lattice — and here it is stronger. On the golden band no offset’s wrecking broke into more than three stretches; offset 4 here is broken into five.
Which is the interesting half of a uniform result
Two things could have made a band come back uniform and only one of them is interesting. It could be that nothing was being tested — that no cut wrecked, or that the same three cuts wrecked at every rise and there was nothing for a change of answer to be a change of.
That is not what happened. The set of wrecking offsets changes on 23 of this band’s 123 steps, so the sweep is measuring something that moves; the family left standing is simply not part of what moves.
Seven, and never eleven, and never four
The family kept is 7, which is the smaller of the counted pair. It is never 11, the larger, and it is never 4 — which is what the golden band’s cuts reach for when they leave 8.
Four is not an arbitrary alternative there. On an 8/13 lattice the four-hop is a sub-multiple of the smaller counted number, and a survivor has to be a neighbour rather than any lag at all. On a 7/11 lattice there is no such sub-multiple, because seven is prime.
That is a difference, and it is not an explanation
It is tempting to make the primality of seven the account, and it is worth resisting for one round of thinking. The claim would be that a band whose smaller counted number has a factor offers a second family to switch to, and a band whose smaller number does not offers none.
The ladder holds too few cases to test it. Its counted pairs are 2/3, 3/5, 5/8, 8/13 on one branch and 1/3, 3/4, 4/7, 7/11 on the other, and only three of those have a composite smaller number. Two of the three are on bands too narrow to cut whole.
The third is the golden 5/8, whose smaller number is composite and whose band is 112 rises. That one is cuttable and would be the test — with the caveat that it shares a branch with the band that has the speckle, so a positive there would not separate the pair account from the branch account.
What a change of answer would have looked like
It is worth naming the thing that is absent, because the absence is the measurement. A change of answer is a rise at which one offset’s cut stops keeping one family and starts keeping another, with both readings taken the same way on stems that differ only in the rise.
On the golden band there are nineteen of them, thirteen at a single offset. Here there are none, and the sweep would have reported one had it been there — the same code, the same tolerances, the same reading.
The tolerance that decides it is the one that says which lag a stem kept, and it is not a threshold anybody tuned: a lag is kept when the hop at that lag holds across the run, and the readings separate into two populations with a gap between them rather than falling either side of a line.
The handover is not where anything happens, again
The claim the thread rests on is that the rise at which the two contact steps change places is not the rise at which the survivor does. Here the handover sits at 57 per cent of the band and nothing at all happens at it.
That is support of a weaker kind than the golden band gives, and it should be counted as such. Nineteen changes none of which is at the crossing is evidence; no changes anywhere is consistent with the claim and consistent with a dozen other things.
What the picture cannot rule out
The sweep reads the family left standing on a stem grown to a fixed length and read over a fixed window. If a change of answer existed but took longer to show than the run allows, this sweep would not see it.
That is not idle. Doubling the run length moved nineteen of twenty-four onsets by more than twenty organs and changed the periodicity verdict on three rows, so run length is known to matter to readings of this kind. It has not been varied on a band.
And what the window cannot rule out either
The same applies to the reading window. The family a cut keeps is read from the top of its run, and the width of that window decides other verdicts in this collection.
Neither has been moved on a band sweep, which is the honest limit of the negative reported here. What can be said is that at the settings every other measurement in the thread uses, this band is uniform.
Why the sweep was worth running anyway
Because the alternative was not knowing. Before it, the honest statement about transition regions was one band has one, with a sample of one; after it, the statement is one band has one and the other wide band does not, with a sample of two.
That is a small sample and it is twice the previous one, and it changed the shape of what could be claimed. A finding that survives a second case gets extended; one that does not gets a boundary drawn round it, and a boundary is the more useful of the two when the thing being bounded is a surprise.
The cost of a null result
Thirty-eight minutes and 1,612 cut stems for a picture with nothing in it. That is the economics of a control and it is worth stating plainly, because a collection that only ran the sweeps likely to produce something would be a collection of positives.
The comparison is with the nine-rise design, which would have taken two minutes and returned the same verdict. It would have been the right verdict and it would not have been worth anything, because nine rises finding nothing is what nine rises do on a band with thirteen islands in it.
Where the survivor does move on this rung
The band is not the rung. The Lucas 7/11 rung runs from a rise of 0.00947 down to 0.0057 and the band covers 0.00922 to 0.00721 of that — about half.
Below the band, still on the rung, the family changes. At a rise of 0.006 three of six wrecking offsets keep a lag of 11 instead of 7, which is the first lag outside the census’s four anything has been found to keep.
So a band holds more than it was built to hold
A band is built to hold the counted pair and the settled divergence while the step ordering reverses. On this rung it also holds the surviving family, and the survivor changes as soon as the band ends.
That is not something the design promised and it is not something the golden band shows — there the survivor changes inside the band. So the two bands disagree about whether a band holds the survivor, which is one more way of saying that the interesting result belongs to one of them.
The uniformity is not the whole band
One more distinction, because the sentence nothing changes on this band is easy to over-read. The pale cells in the picture are rises where an offset recovers rather than wrecks, and there are plenty of them: offset 4 has no answer at 97 of the 124 rises.
So the band is uniform in the family kept where a family is kept at all, and the set of rises where one is kept is different for each offset. Those are two separate readings of the same table and only the first is uniform.
Reading a table with two states in it
Every cell of the sweep is one of three things: a cut that wrecks and keeps 7, a cut that recovers, or an offset that was never tried. Collapsing the second and third would be the easy mistake, and it would turn this offset recovers here into this offset was not measured here.
The sweep tries every offset out to the front and two past it at every rise, so the third state does not occur inside the band. It is worth saying because nothing behind the front wrecks is a separate result that the design depends on and does not re-derive.
What replicates and what does not
Two findings came from the first band and they have come apart. That which offsets wreck moves with the rise replicates, and more strongly here. That the family kept changes inside a band does not replicate at all.
A pair of results that separate under replication is more informative than a pair that both hold, because it says the two were never one finding. They were reported together because they came out of the same table.
The picture is the argument
There is not much to say about a uniform picture that the picture does not say, which is why this essay is mostly about what would have shown up in it.
A reader who wants one sentence should look at the two blocks in the hero of the essay that cut this band: the upper one has a speckled middle and the lower one does not, at the same resolution, on the same instrument, thirty-eight minutes apart.
A second branch is not a second sample
There is one more reason not to call this a replication and then stop. The two bands differ in branch, in counted pair and in width all at once, so a difference between them has three candidate causes and the sweep separates none of them.
That is the ordinary situation when a ladder offers eight rungs and only two of them are wide enough to cut. It is worth writing down rather than left implied, because a reader who takes the speckle is one band’s as the speckle is the golden branch’s has read more into two cases than two cases hold.
What the sweep would have to be to say more
An account of when a band carries a transition region needs a population, and the population would have to be bands rather than rises. The ladder has six, one of which is a control, and two of which have now been cut whole.
Cutting the other three is about an hour altogether — 70, 86 and 16 rises — and would take the sample from two to five. That is the cheapest thing this thread could do next and it is worth saying that it is cheap, because the instinct after a surprising result is to build a new instrument rather than to point the old one somewhere else.
What is already known about the narrow three
Two of the three do not wreck at any offset at their coarse ends, because a coarse enough stem cannot be wrecked by a single removal at all. So a sweep of the 3/5 band and the Lucas 3/4 band would be measuring something different from a sweep of the two wide ones.
The Lucas 3/4 is a control for a separate reason as well: its two contact steps stay within four parts in a thousand of each other across the whole band, so the ordering changes hands three times inside it and neither end is separated enough for an ordering to mean anything.
What a reader should carry
That a band can be cut at every one of its rises and come back with nothing inside it, and that this is a result rather than a failure.
And that the value of a null depends entirely on its resolution. Nine rises finding nothing on this band would have been worth very little; 124 rises finding nothing is what makes the other band’s speckle a property of that band.
What the picture at the top shows
Five rows and 124 columns, coarse on the left, with a mark wherever a single removal at that offset wrecks the stem. Three rows are solid all the way across; one begins a third of the way in; one is broken into five stretches with long gaps between them.
Every filled cell is the same tone, and that is the finding. On the other band the same picture has two tones in its lower rows, arranged in islands.
The one line
Five offsets, 124 rises, 1,612 cut stems, and one family kept in every cell that holds one: the Lucas 7/11 band has no transition region, no islands and nothing to fit a period to.
Which offsets wreck moves across it, and more than on any band measured before; which family they keep does not move at all.
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.
- Three offsets, three crossings — both name ablation, claim testing, control, handover, honest limits, lattice offset, negative result, resolution, rise, rung, sampling
- The side the census sat on — both name ablation, claim testing, control, handover, honest limits, lattice offset, negative result, rise, rung, sampling
- The wrecking set moves again — both name ablation, claim testing, contact family, handover, honest limits, lattice offset, replication, rise, rung, sampling
- Six lattices were not enough — both name ablation, claim testing, control, honest limits, lattice offset, negative result, rise, rung, sampling
- The exception was already labelled — both name ablation, claim testing, control, handover, honest limits, lattice offset, negative result, rise, rung
- The ordering on six bands — both name ablation, claim testing, control, handover, lattice offset, negative result, resolution, rise, rung
Named objects
A flat tag is an object no other essay names yet.
AblationClaim testingContact familyControlHandoverHonest limitsLattice offsetNegative resultReplicationResolutionRiseRungSampling