core/docs/decisions/ADR-0131.G.4-multi-clause.md

# ADR-0131.G.4 — Capability axis: multi-clause composition (conjoined subjects, conjoined objects, embedded quantifiers)

**Status:** Proposed
**Date:** 2026-05-23
**Author:** CORE agents + reviewers
**Parent:** [ADR-0131.G](./ADR-0131.G-gsm8k-coverage-probe.md)
**Depends on:**
[ADR-0126](./ADR-0126-candidate-graph-parser.md) (candidate graph),
[ADR-0127](./ADR-0127-en-units-v1.md) (substance qualifier policy),
[ADR-0131.3](./ADR-0131.3-bounded-grammar.md),
[ADR-0132](./ADR-0132-binding-graph-data-model.md)..[ADR-0135](./ADR-0135-question-target-binding.md)

---

## Context

GSM8K paragraphs frequently introduce starting state via within-sentence
composition the per-statement candidate parser refuses today:

| Baseline refusal sentence | Capability missing |
|---|---|
| `Aaron and his brother Carson each saved up $40 ...` | conjoined subject + distributive `each` |
| `Francine has five full boxes of crayons and 5 loose crayons` | conjoined object NPs sharing a verb |
| `Ella has 4 bags with 20 apples in each bag and six bags with 25 apples in each bag` | embedded quantifier + conjunction |

This is the **highest-risk axis** of ADR-0131.G's four near-term
capability extensions. Multi-clause emission means the round-trip
filter does more work; multi-candidate ambiguity makes confabulation
risk higher. Refusal-first stays paramount: admission gains must be
small and load-bearing.

---

## Decision

Land four within-sentence multi-clause extractors in
`generate/math_candidate_parser.py`. All emit
`CandidateInitial` records (initial state, not operations — the
shapes here introduce starting holdings, they do not mutate state):

| Extractor | Shape (closed set) | Emission |
|---|---|---|
| `_conj_subject_each_candidates` | `<A> and [his/her/their <kin>] <B> each <verb> <N> <unit>` | **two** `CandidateInitial` (one per actor), same `(N, unit)` |
| `_conj_object_candidates` | `<E> has <N1> <unit1> and <N2> <unit2>` | **two** `CandidateInitial` for the same entity; same-unit conjuncts refuse |
| `_embedded_quantifier_candidates` | `<E> has <N> <container> with <M> <unit> in each [<container>]` | **one** derived `CandidateInitial` with `value = N*M, unit = <unit>` |
| `_embedded_quantifier_candidates` (conj branch) | `<E> has <N1> <C> with <M1> <U> in each ... and <N2> <C> with <M2> <U> in each ...` | **one** SUM `CandidateInitial` with `value = N1*M1 + N2*M2, unit = <U>`; mixed-unit conjuncts refuse |

Wired into the existing `extract_initial_candidates` public entry
point — the binding graph (`math_candidate_graph._filtered_statement_choices`)
already consumes through that path; no graph-side edit required (the
read-only audit concluded composed candidates are reachable through
existing edges).

### Closed-set discipline

- **Distributive `each` only.** Surface markers `together`, `in
  total`, `altogether` immediately abort emission (explicit
  contradiction with distributive reading). Pinned by
  `test_refuses_each_with_together` /
  `test_collective_without_each_refuses`.
- **Two-way conjunction only.** Three-way `A and B and C each ...`
  is out of closed-set shape and refuses by non-match.
- **Same-unit conjoined object refuses.** Two same-unit conjuncts
  on the same entity (`Sam has 5 dimes and 3 dimes`) would silently
  collide under the solver's `state[(entity, unit)]` overwrite
  semantics (`math_solver.py:206`); refusing keeps `wrong == 0`.
- **Ambiguous `each` scope refuses.** `Ella has 4 bags with 20
  apples in each box` — `box` ≠ `bags` ⇒ refuse.
- **Mixed-unit conjoined embedded refuses.** Apples + pears cannot
  be summed.
- **No cross-sentence state.** Multi-sentence inputs are processed
  per-sentence; pronouns / coreference across sentences stay
  refused (out of within-sentence axis scope).

### CandidateInitial anchor widening

`CandidateInitial.__post_init__` whitelists a narrow set of
initial-state-introducing verbs needed for the conjoined-subject-each
shape (`saved`, `earned`, `got`, `received`, `bought`, `made`,
`paid`, plus their inflected variants). The widening is keyed on
lowercase tokens; the `_token_in` check in
`math_candidate_graph._initial_admissible` confirms the anchor word
appears in source. Verb-class widening for the *general* parser
remains G.1's scope; G.4 widens only what conjoined-subject-each
needs.

### Derived-value provenance

Embedded-quantifier and conjoined-embedded emissions carry a
*derived* value (`N*M` and `N1*M1 + N2*M2` respectively) that does
not appear as a single source token. The round-trip filter's
"value grounds in source" check (`_value_grounds`) is satisfied by
anchoring `matched_value_token` on the **per-container `M`** (or
**first per-container `M1`** for the sum). This is a deliberate,
documented widening of the source-grounding spirit: the *components*
of the derived value all appear in the source, and the parser
commits to the canonical arithmetic composition. Refusing on
component-mismatch (mixed units, wrong container scope) and refusing
on indefinite quantifiers in any value slot together keep the
derivation honest. The alternative — emitting two flat candidates
for conjoined-embedded — was rejected: under the solver's
overwrite-on-collision semantics it would silently drop one
conjunct's contribution, breaching `wrong == 0`.

### No graph-side edits

`math_candidate_graph.py` is unchanged. Multi-candidate emission
flows through the existing per-sentence choice space + Cartesian
product; conjoined-subject-each and conjoined-object emissions land
in `_filtered_statement_choices` like any other initial candidate.
The solver's `state[(entity, unit)]` model naturally accommodates
distinct entities (each-shape) and distinct units (object-shape);
collision-prone shapes refuse at the parser. This decision is the
"read-only audit only edit if composed candidate is unreachable"
posture from the brief.

### Curated coverage cases (G.4 axis lane)

`evals/math_capability_axes/G4_multi_clause/v1/cases.jsonl` —
**32 cases**:

| Category               | Cases | Notes |
|------------------------|-------|-------|
| `conj_subject_each`    | 6     | incl. kin-appositive, word-form value |
| `conj_object`          | 6     | distinct-unit conjuncts only |
| `embedded_quantifier`  | 6     | with + without explicit `container2` |
| `conj_embedded`        | 6     | same-unit only |
| `refusal`              | 8     | together / altogether / 3-way / cross-entity / scope-mismatch / mixed-unit / cross-sentence / same-unit collision |

Runner emits a deterministic `report.json`; `wrong == 0` is the gate.

### Deferred (out of scope for G.4)

- **Cross-sentence coreference** (`Aaron has 5. He gives 2 to
  Bob.`) — needs per-discourse state; pinned as refusal probe.
- **Ellipsis** (`Aaron has 5 apples, Carson 3`) — needs verb
  reconstruction; pinned out-of-scope.
- **Three-way+ conjunctions** (`A and B and C`) — combinatorial
  explosion + ambiguity; deferred to a future axis.
- **Collective readings** (`A and B saved $40 together`) —
  explicitly refused; collective semantics needs a different
  binding-graph node type.
- **Currency / unit prefix** (`$40`) — refused at the value slot
  (the `$` is not a `_VALUE` character). Deferred to **G.3
  numeric-literals axis**, which is the natural place for currency
  / percentage / decimal literal handling. Documented impact on the
  GSM8K probe gate (case 0026 stays refused).
- **Same-unit conjoined object summation** — would require either
  parser-side sum (analogous to conj-embedded) or solver-side
  state-merge; deferred until a sum-shaped CandidateInitial proves
  necessary outside this axis.
- **Solver / binding-graph changes.** If a multi-clause case parses
  but does not solve, that's a downstream gap and gets its own ADR.

### GSM8K-probe gate (chosen)

G.4 gates on:

> **Multi-clause statement-clause refusals in the candidate-graph
> probe (`evals/gsm8k_math/train_sample/v1/report.json`) strictly
> decrease.**

Counter (in `test_gsm8k_candidate_graph_multi_clause_refusals_decreased`)
matches refused cases citing a statement-clause refusal whose
embedded sentence text contains a multi-clause anchor pattern
(`each <init-verb>`, `with N <unit> in each`, or `has N <unit> and N
<unit>`).

| Probe report                                | Baseline (origin/main 481e0c3) | After G.4 | Δ  |
|---|---|---|---|
| Multi-clause statement-clause refusals (`report.json`) | 2                              | 1         | −1 |
| `wrong` (`report.json`)                     | 0                              | 0         | 0  |
| `admission_rate` (`report.json`)            | 0/50                           | 0/50      | 0  |
| Legacy `train_sample_coverage_report.json`  | byte-identical                 | byte-identical | 0 |

Baseline-2 cases: `gsm8k-train-sample-v1-0026` (`Aaron and his
brother Carson each saved up $40 ...` — refused on `$40` value
slot; deferred to G.3) and `-0042` (`Ella has 4 bags with 20 apples
in each bag and six bags with 25 apples in each bag.` — now parses,
refusal moves to question layer). `admission_rate` does not rise
because downstream layers (question-form admission for derived
initial states) are out of G.4 scope.

### Legacy probe report (refreshed, byte-identical)

`evals/gsm8k_math/train_sample/v1/train_sample_coverage_report.json`
runs through `generate.math_parser.parse_problem` (legacy
first-match-wins), which G.4 does not touch. Refreshed and pinned
via `test_gsm8k_legacy_probe_safety_rail_intact`.

---

## Invariants

- **`g4_wrong_count_is_zero`** — every G.4 axis case passes or
  refuses; no case admits a wrong shape. Pinned by
  `test_runner_wrong_count_is_zero`.
- **`g4_closed_set_refusals_hold`** — all 8 refusal probes admit
  zero multi-clause candidates. Pinned by
  `test_refusal_cases_emit_no_admitted_multi_clause` (parametric).
- **`g4_distributive_each_only`** — `each ... together` and `each
  ... altogether` refuse. Pinned by
  `test_refuses_each_with_together`.
- **`g4_cross_sentence_refuses`** — multi-clause extractors do not
  fire across sentence boundaries. Pinned by
  `test_cross_sentence_pronoun_refuses_multi_clause`.
- **`g4_report_deterministic`** — `report.json` is byte-equal across
  back-to-back runs.
- **`gsm8k_safety_rail_intact`** — `admitted_wrong == 0` on both
  GSM8K probe reports.
- **`gsm8k_multi_clause_refusal_strictly_decreased`** — chosen G.4
  gate.

---

## Acceptance evidence

- `evals/math_capability_axes/G4_multi_clause/v1/runner.py` exits 0
  with `wrong == 0` on all 32 curated cases.
- `tests/test_adr_0131_G4_multi_clause.py` (26 tests): per-shape
  emission, refusal-set, distributive-only policy, cross-sentence
  refusal, runner byte-equality, GSM8K-probe gate.
- Candidate-graph probe `report.json`: multi-clause statement
  refusal count 2 → 1 (case 0042 moves from statement to question
  refusal).
- Legacy probe `train_sample_coverage_report.json` refreshed and
  byte-identical.
- B3 lane + ADR-0126 candidate-graph tests + ADR-0131.G probe
  tests all pass (95/95 across the regression sweep).

---

## Consequences

- The candidate-graph topology can now see four multi-clause
  initial-state shapes the per-statement parser previously refused.
  Downstream question-form admission for derived initial states
  (case 0042) becomes a natural next unblock.
- The same Cartesian-product / "branches that disagree → refuse"
  decision rule handles the new multi-candidate emissions; no
  graph-side edits, no admissibility weakening.
- Highest-risk axis lands without breaching `wrong == 0`:
  multi-candidate emission stays tightly scoped, refuses on every
  documented adversarial probe, and the derived-value emissions
  refuse on every shape-mismatch (mixed unit, scope-mismatch,
  collision-prone same-unit).
- Future axes inherit the same axis-lane harness layout under
  `evals/math_capability_axes/`.

---

## Out of scope

- **Solver changes.** If a multi-clause case parses but does not
  solve, the gap is downstream; file a follow-up ADR (no solver
  stubs, no admissibility relaxation).
- **Currency / numeric-literal handling.** Case 0026 (`$40`) stays
  refused; the G.3 numeric-literals axis is the natural place.
- **Three-way / ellipsis / cross-sentence shapes.** Deferred per
  the closed-set discipline.
- **Probe runner contract.** ADR-0131.G pinned `run_lane` as the
  legacy probe's contract; G.4 does not change that. The
  candidate-graph probe (`report.json`) is the measurement surface
  that moves.