Concept

Version history — where it appears

Successive revisions of one file, which is the collection a compressed index is built for. Its changes are localised and its documents grow: several consecutive revisions can differ in nothing at all, which is what a model of an edit as a scattered substitution does not reproduce.

Named by 5 essays across 4 fields — each of them below, with the objects they name alongside it.

twelve essays — runs0.491generated, matched0.109twelve essays — phrases0.213generated, matched0.046eight source modules — runs0.461generated, matched0.122eight source modules — phrases0.210generated, matched0.050ten revisions of one file — runs0.126generated, matched0.113ten revisions of one file — phrases0.067generated, matched0.047per character24,576 characters a partdivergence 0.02

A corpus that was not generated

Every collection in five strands has been copies of a generated text with a fraction of its characters replaced — three numbers, one dial. Here is one that was not — twelve essays, eight source modules, ten revisions of one file — measured beside the model of it.

text · Document
02468101214mean 5.71depthshare of the collectionten revisionstwelve essays75,658 characters · 2,966 phrasesworst 14, mean 5.71

The shape of a real history's depth

Four essays here are about capping how far an extraction follows a chain of copies, and every number in them came from a generated collection. Here is the depth histogram of a real version history, which is a bell, and of twelve unrelated essays, which is nearly the same bell.

text · Parse
05101520510revisions in the collectiondepthone revision alone: 8worst depthmean depthfourteen revisions of another9 generations added exactly one

One revision, one level

The cap ladder assumed depth is generations of copying. On a real file it is exactly that — one more revision, one more level, nine times running — plus eight levels the first revision already had before any history existed.

structures · Parse
ten revisions of one filecap 10worst 14 · mean 5.7fourteen revisions of anothercap 10worst 17 · mean 7.2twelve unrelated essayscap 10worst 14 · mean 4.9eight source modulescap 10worst 78 · mean 5.9a generated collectioncap 10worst 13 · mean 4.6within a twentieth of the free parsefour to eight was the model

The cap that would ship

The published sweep put the knee at four to eight. On four real collections it is at nine to twelve, a cap of one costs forty-eight times the free parse rather than twenty-one, and the number a system should actually set is none of those.

practice · Parse
1.0%10.0%0.11fraction of characters changedper characterthe real runsthe real phrasesgenerated runsgenerated phrasesten revisions of one file · 24,580 characters2.32% against 3.24%

The dial that has no setting

The generator has one parameter. The real version history's run count asks it for 2.3% and its phrase count asks for 3.2% — and the reason is not that the dial is badly calibrated. Real edits average 7.3 characters a block and generated ones average 1.04.

wrong · Document

Named alongside it

The objects these essays reach for when they reach for this one.

CorpusPhrase countControlGenerated collectionDepthExtractionParseCopyHistogramMeasurementRepetitionRun count

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