core/docs/adr/ADR-0189-comparative-verb-unit-widening.md

ADR-0189 — Comparative reading: anchor-verb widening + multi-word units

Status: Proposed (implemented in this PR). Extends ADR-0131.G.2 (candidate-graph comparative extractors). Serving-path capability; landed wrong=0-proven.

One line. The candidate-graph comparative extractor read only has/have

• single-word units, so real-GSM8K comparatives (Brooke **does** three times as many **jumping jacks** as Sidney) didn't parse. This widens the anchor-verb set (excluding polarity-inverting verbs) and admits 1–2-word units. It feeds the existing ADR-0123 compare_multiplicative/compare_additive solver; wrong=0 is preserved (G2_comparatives 29/29; train_sample 3/47/0 byte-identical).

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1. The gap (microscope finding, 2026-05-29)

The candidate-graph parser emits no comparative operation for the most common real-GSM8K comparative surfaces, even though the solver already supports them (ADR-0123 compare_additive/compare_multiplicative, fully wired in math_solver). Measured: comparatives are a dark statement in 17 places, blocking 15 of the 47 refused train_sample cases.

Two extractor limits caused the misses (_comparison_anchor_verb() was (?:has|have) and units were \w+):

• Verb coverage. does/collected/gained/studied/makes/… were not recognized. (ADR-0131.G.2 deferred this explicitly: "past-tense + lemma-widening are deferred … to keep the precedence story narrow" — a scope limit, not a wrong=0 constraint.)
• Multi-word units. jumping jacks (case 0024) could not match.

2. The change

• generate/math_candidate_parser._comparison_anchor_verb() — widen to the already-vetted legacy math_parser._COMPARE_VERB lemmas plus the production/activity verbs seen in real GSM8K comparatives. Deliberately EXCLUDES polarity-inverting verbs (lose/lost, win/won, spend/spent, use/used, give/gave, sell/sold) — admitting them could read a comparison backwards and breach wrong=0.
• The two multiplicative regexes admit an optional second unit word (\w+(?:\s+\w+)?), grounded via the existing multi-word branch of _unit_grounds.

3. wrong=0 evidence

• G2_comparatives lane: 29/29, wrong=0 (the dedicated comparative lane).
• G3_numerics 20 correct / 0 wrong; G4_multi_clause 32/32; train_sample 3/47/0 byte-identical (no flip, no wrong).
• Polarity-inverting verbs proven refused (test_…_polarity_inverting_verb_not_admitted, test_spend_verb_not_admitted) — failing-under-violation.
• The round-trip filter is unchanged: the comparator anchor (twice/N times/ more/fewer) and the reference actor still must ground.

4. Honest scope — a necessary component, not a standalone solve

This widening flips zero train_sample cases by itself, because every comparative-blocked case also needs a composing partner the reader still lacks (e.g. case 0024 needs Sidney's 20+36+40+50=146 day-of-week aggregation and multi-word counted-noun injection before Brooke = 3 × 146 = 438 can solve). The comparative + question chain is proven to compose correctly in isolation (Sidney has 146 apples. Brooke has three times as many apples as Sidney. → 438). This ADR ships the comparative component; the first metric flip (3/47/0 → 4/46/0) lands when its companion capability (aggregation / multi-word-noun injection) lands for a shared target case.

5. Why this obeys the standing principles

• Decode, don't guess. The engine could already reason about comparison (ADR-0123 solver); this teaches it to read the comparison — closing a comprehension gap, not adding a stored answer.
• General, not overfit. A widened closed verb set + multi-word units is a fundamental construction across 15 cases, not a per-case surface regex.
• wrong=0 > coverage. Polarity-inverting verbs excluded; G2 lane 29/29; serving 3/47/0 byte-identical; round-trip filter untouched.
• No contradiction with in-use ADRs: extends ADR-0131.G.2's extractor and feeds the ADR-0123 solver unchanged.