llm-ingestion-okf/docs/2026-09-08-rangeringsbom-sammensatte-ord.md

The compound-word ranking miss: a degenerate signal, not a matcher, 2026-09-08

A consumer asked the N500 bundle about vann- og frostsikring in a subsea tunnel and got eight excerpts, none of which covered the subject; the bundle covers it on 16 concepts. The consumer behaved as the contract asks — it answered [sourced-not-sufficient] and named its denominator — so the miss is the ranker's (docs/2026-09-08-claude-code-skill-vilkaarlig-bundle.md § 5).

The order proposed two sites for one rule: the tokeniser, or the fusion. The measurement chose for us, and it chose neither of the two mechanisms the order named. The tokeniser already resolves the compound, and the fusion's defect is not a weight — it is the tie-break in a signal that separates nothing.

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0. What IS measured, and what is NOT

Measured. The miss reproduced with a command and a denominator; the three per-signal ranks of the covering concepts; the document prior's distinctness on two corpora; the rule's effect on four cases; every known-negative the order names, both values; six default payload digests against a frozen HEAD; the contract checker on eight payloads; the skill generator's output before and after; the full suite.

Known-positive, run first. Every figure this session builds on was reproduced on this machine before any after-column was read:

#	known-positive	source	measured here
1	files matching frostsikring	C1 § 5	17, case-insensitively, index.md among them
2	files matching vann- og frostsikring	C1 § 5	10
3	files matching undersjøisk	C1 § 5	13
4	the miss itself: covering concepts in the cut	C1 § 5	0
5	hit@8 over the six published questions	2026-09-07 § hit@k	5 of 6, ranks 1,1,1,1,1,–
6	the three requirement lookups, rank of 8	O2c § 3	1, 1, 1
7	K2 bundle, whole tree	Arm C § "did not move"	1108 files, 9cd74519…
8	suite before the session	STATE (round 110)	1388 passed

One known-positive did NOT reproduce, and the deviation is the order's own literal. The order names the S7 control payload as 2ae46f68…, 169 573 B. Measured on frozen ff79cfa (git archive into a scratch tree, __file__ asserted), that command produces c759a657…, 171 614 B. The literal is not wrong, it is stale: it was published at 116d3e1, and a37d5ce, 17c49fc and c95d189 each widened the excerpt form afterwards. No document restates it. The row is therefore measured as "byte-identical against HEAD", which is what it exists to prove, and the stale literal is reported rather than quietly matched.

NOT measured.

• Whether a live model answers better. This measures a ranking. Delivered is not read.
• o200k_base token counts. No encoder is installed and the single-dependency rule does not admit one. Every figure is in BUDGET_UNIT plus sha256.
• Whether the rule helps a third corpus class. Two were measured (the three N-bundles and K2). A corpus whose document prior is neither degenerate nor coarse is unmeasured, and the flag's default reflects that.

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1. The reproduction, with the command and the numbers

The order asks for the question C1 § 5 used, quoted. It is not in that document — § 5 describes the question in prose ("about water and frost protection in a subsea tunnel") and quotes no line. The question below is the order's own wording, and it is marked as such rather than presented as C1's:

python3 tools/okf_consume.py ~/repos/vegnormal-okf/build/ferdig/n500-2024 \
  --question "Hvilke krav gjelder vann- og frostsikring i undersjøisk tunnel?" \
  --out /tmp/o4-baseline.json

270 concepts, 8 delivered, 262 withheld. 0 of the 16 covering concepts — the concepts whose title or body says frostsikring, case-insensitively — is in the cut. The best of them fuses to rank 14.

The eight delivered, and the three covering concepts nearest the cut, with the per-signal ranks that decide the fusion:

	fused	body	title+id	doc prior	lexical	title
delivered 1	1	17	6	4	6	Krav 4.3—1 Tunnelportaler
delivered 2	2	24	1	50	7	Krav 3.2—2 Utslipp av vann fra tunnel
delivered 3	3	138	5	1	4	Krav 5.3.6—1 Fjernstyrte bommer
covering 1	14	6	33	130	7	Krav 8.4.2—1 Frostisolering med PE-skum eller XPS
covering 2	39	34	30	121	6	Krav 9.3.2—2 Fundament, omfylling og frostsikring
covering 3	44	25	101	63	5	Krav 1.1—2 Generelle bestemmelser

The best covering concept answers 7 of 7 question tokens — more than any delivered one — and leads the body signal at rank 6. It is not invisible to the matcher. It is behind on one signal: the document prior, at rank 130.

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2. Why it is not a matcher miss (the order's alternative A, falsified)

Three measurements, each of which alone rules the tokeniser out as the site:

1. The compound is already resolved. normalise("vann- og frostsikring") returns ('vann', 'frostsikring') on HEAD. The hyphen splits, og falls below MIN_TOKEN_LENGTH. There is no coordination left for a rule to undo.
2. The prefix rule already bridges the inflections. tokens_match('frostsikring', 'frostsikringen'), ('vann', 'vannsikring') and ('undersjøisk', 'undersjøiske') are all True at MIN_SHARED_PREFIX = 4.
3. The covering concept already scores the maximum. Its lexical overlap is 7 of 7 question tokens. A rule widening the tokeniser cannot raise 7.

Recorded as a test rather than as a memory: tests/test_tie_shared_rank.py::test_the_hyphen_and_og_coordination_is_already_resolved_by_the_tokeniser, green on HEAD and labelled a characterisation.

One thing the same measurement DID surface, and it is not fixed here: the prefix rule over-matches in the other direction. undersjøisk matches under, so its document frequency is 159 of 270 — a term that should be one of the rarest in the question reads as one of the commonest. That belongs to the rarity weight (--rarity-weight, already shipped and already off), and this session was allowed one rule.

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3. What it is: a signal that separates nothing still orders everything

RRF consumes ranks only, so concept_scores produces a rank for every concept in every signal — including a signal that gave them all the same score. The declared tie-break, (-score, concept_id), then orders that group by concept_id, and the fusion reads the result as though it were a measurement.

On N500 the concept ids are UUIDs and the document prior is degenerate:

corpus	documents	distinct prior values	concepts sharing one value
N500	2	2	269 of 270
K2	39	6	—

So on N500 the third signal contributed alphabetical UUID order, spread from 1/61 down to 1/329. That spread is worth more than several positions on the two signals that did the measuring, and it is what put a concept answering 7 of 7 tokens behind concepts sharing only tunnel and vann.

The rule. tie_shared_rank: every concept a signal scores equally takes that score group's first position, so a signal that separates nothing contributes an identical constant to every concept and orders none of them. It is general — no word list, no corpus constant, no new number except the group boundary the scores themselves define.

The first position rather than the middle, and that was measured too: the midpoint variant put the best covering concept at rank 5 where the first puts it at 3, and neither changed the three lookups. First is kept because under it a non-separating signal contributes an identical constant, which is the whole claim; the midpoint still varies with the size of the group a concept lands in.

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4. The known-negative table, both values

Flag --tie-shared-rank, off and on. Every row measured in one run, /tmp/o4/kn.py.

row	off	on	verdict
N100 lookup Krav 3.3.1-13, rank of 8	1	1	holds
N200 lookup Krav 2.9.2-12, rank of 8	1	1	holds
N500 lookup Krav 10.2-2, rank of 8	1	1	holds
hit@8 over the six published questions	5 of 6	4 of 6	FALLS
— per-question rank	1,1,1,1,1,–	1,–,1,1,1,–	row 2 lost
S7 control question, default command	c759a657… 171 614 B	5f4cd665… 145 228 B	moves (on purpose)
K2 bundle, whole tree	9cd74519… 1108 files	9cd74519… 1108 files	holds
okf_contract_check, 8 payloads	exit 0	exit 0	holds
the O4 miss: best covering rank	14	3	closes
the O4 miss: covering concepts in the cut	0 of 16	2 of 16	closes

The two concepts the rule delivers are Krav 8.4.2—1 Frostisolering med PE-skum eller XPS and Krav 9.3.2—2 Fundament, omfylling og frostsikring for ledninger.

Default stays OFF, by the order's own rule: it requires every row to hold and the miss to close. The miss closes; the hit@8 row does not.

Why row 2 falls, decomposed rather than guessed

row	gold concepts	best fused, off	best fused, on
1	1	1	1
2	49	1	28
3	20	1	1
4	43	1	1
5	11	1	1
6	5	11 (not delivered)	91 (not delivered)

K2's document prior is not degenerate: 6 distinct values over 39 documents. There the tie-break groups are large but the signal does separate, and row 2's gold happened to sit early in its group — that is, the noise was, on that one question, pointing the right way. Removing the noise removed a benefit that was never a measurement. That is an honest reason to keep the rule available and an equally honest reason not to make it the default: a rule that is right in principle and loses a published row is a caller's choice, not a library's.

Row 6 was already the known 1-of-6 shortfall and is not delivered either way.

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5. The default did not move, measured against a frozen HEAD

Six payloads built from git archive ff79cfa into /tmp/o4/head (with __file__ asserted to be under that tree, so an editable install cannot be read by accident) and from this working tree with both new flags omitted:

payload	digest
N100 lookup	a2a91d8b99157a0c, 58 082 B
N200 lookup	0c828a5f8c432864, 144 932 B
N500 lookup	ad2b35a556278553, 41 364 B
N500 O4 miss	d4a75828c147d9e9, 47 056 B
S7 control	c759a657dbb41d71, 171 614 B
K2 price question	f17c8725ee6bbe1a, 167 360 B

6 of 6 identical. No consumer's bytes move because this session happened.

tools/okf_skill.py likewise: SKILL.md and references/example-payload.json are byte-identical apart from the absolute paths each copy writes about itself.

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6. withheld names what was dropped — behind a flag, and here is why

C1 § 5's second observation: a withheld entry carries concept_id and rule and no title, so a reader told 262 concepts were withheld cannot tell what without reading the bundle, which § 2.2 forbids.

The code is cheap — 11 lines, well inside the order's 20-line bar. The bytes are not, and that is what moved the decision:

	without title	with title
N500 payload	41 364 B	57 023 B (+37.9 %)
N100 payload	58 082 B	88 251 B
N200 payload	144 932 B	215 148 B
K2 bookkeeping (629 concepts, everything not an excerpt)	~75 KB	122 704 B

The last row is the one that decided it. skills/okf-consume/SKILL.md — a tracked file — publishes the breaking point as "at 629 concepts it is ~75 KB … at roughly 8 000 concepts the withheld list alone approaches the 120 000-byte limit". With titles on by default that sentence becomes false immediately: at 629 concepts the bookkeeping is already past the limit. The generated skill's own figure moved from a 1206-concept ceiling to 762.

So --withheld-titles, off by default. On, every one of N500's 262 withheld entries carries its title; off, the entries are {concept_id, rule} exactly as before, and the eight contract-checked payloads all exit 0 either way.

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7. What did NOT close

• 14 of the 16 covering concepts are still outside the cut with the flag on. Rank 3 is not rank 1, and k = 8 over 270 concepts is a narrow door.
• The over-matching prefix. undersjøisk reads as 159-of-270 common. One rule per session; this was not it.
• hit@8 row 6 — unchanged, not delivered either way, both before and after.
• The default. Two flags shipped this session and both are off. Whether either should be on is in the session's decision block, not decided here.

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8. Tests and gates

New file tests/test_tie_shared_rank.py, six tests: two characterisations (green on HEAD, marked as such), and four that were red on HEAD — the ranking difference (8 vs 1 on a synthetic bundle, two different numbers rather than one predicate two branches share), the byte-identity of the default, the delivered set under the flag, and the CLI defaults.

Three tests added to tests/test_okf_consume.py for --withheld-titles: the titled form, the untitled default (set(entry) == {"concept_id", "rule"}), and the byte cost. One existing assertion was widened from a whole-dict equality to the two fields it is actually about, so an unrelated widening of the withheld form cannot fail a cost-vocabulary test.

gate	before	after
pytest -q	1388 passed	1397 passed
ruff check src tests tools	clean	clean
ruff format --check	clean	clean (92 files)
mypy --strict src	17 files, clean	17 files, clean