# LINEAGE_INDEPENDENCE -- Citation-Network Inputs to Dimension D3

**Provenance:** Phase 3 S07 (R7.1 PASS, R7.2 PASS, R7.3 PARTIAL). Greenberg 2009 (BMJ 339:b2680); Kessler 1963 (bibliographic coupling); Small 1973 (co-citation); Bikhchandani-Hirshleifer-Welch 1992 (information cascades); Newman 2001/2004 (co-authorship, community detection).

**Purpose:** Convert lineage metrics (computed upstream by Multi-Corpus Retrieval Router per R7.3) into the D3 score of the shared schema. D3 asks: is this source genuinely independent from the other admitted sources for this claim, or does it inherit the claim via a common ancestor, co-author cluster, or citation cascade?

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## Input metrics (consumed, not computed here)

Received per source per claim:

- `bibliographic_coupling_score_vs_admitted_set` -- Kessler BC = |R_i intersect R_j| / sqrt(|R_i||R_j|), averaged against other admitted sources for this claim.
- `amplification_class` in {original-data, amplification, invention} -- Greenberg 2009 classification.
- `ancestor_overlap_depth3` -- count of shared ancestor papers within 3 hops across admitted sources.
- `founder_concentration` -- share of citation paths through top-3 ancestors for this claim's admitted set.
- `community_modularity_Q` -- Leiden modularity across the admitted set's citation subgraph.
- `coauthor_distance_min` -- shortest co-authorship path to another admitted source (0 = same author).
- `shared_funder_flag` -- boolean.

## D3 scoring thresholds (Phase 3 defensible starting values)

Phase 3 S07 noted thresholds are PARTIAL -- defensible starting points requiring per-discipline calibration during Phase 9 eval. These are the starting values:

- `BC < 0.10` AND `amplification_class = original-data` AND `ancestor_overlap_depth3 = 0` AND `coauthor_distance_min >= 3`: **D3 = 5** (genuinely independent).
- `BC in [0.10, 0.25)` AND `amplification_class = original-data`: **D3 = 4**.
- `BC in [0.25, 0.40)` OR `ancestor_overlap_depth3 = 1`: **D3 = 3** (partial overlap -- Kessler's 0.25 BC threshold flagged as evidentially dependent).
- `BC >= 0.40` OR `amplification_class = amplification` OR `founder_concentration > 0.60`: **D3 = 1** (amplification-class with concentrated provenance).
- `amplification_class = invention` OR `community_modularity_Q > 0.70` AND `founder_concentration > 0.80`: **D3 = 0** (citation-cascade confirmed, invention-class source, or tight echo chamber).

`coauthor_distance_min <= 2` OR `shared_funder_flag = true` reduces the score by 1 (floor 0) -- author / funder cluster is partial dependence.

## Set-level re-computation (SKILL.md Step 8)

D3 is a SET-level property. When multiple sources are scored for the same claim, re-run D3 across the admitted set:

- Compute amplification ratio = (amplification-class count) / (total admitted count) for the claim.
- If amplification ratio > 0.70: emit a Greenberg-cascade Surprise Register write (per SURPRISE_WRITE.md), mark the claim as `lineage_collapsed=true`, and downgrade every source's D3 in this set by 1 (floor 0).
- If `founder_concentration > 0.60` at set level: add a one-line note in each source's D3 rationale "set-level founder concentration X -- narrow provenance."

## Greenberg 2009 worked example (reference)

Greenberg's 242-paper, 675-citation network on the beta-amyloid / inclusion-body-myositis claim revealed 220,553 citation paths tracing back to a tiny founder set. Papers that APPEARED to "independently" support the claim inherited it via citation chains. This is the archetype of a D3 = 0 / D3 = 1 case, and the archetypal Surprise Register "echo-chamber detected" trigger.

**Operational note:** D3 is the single dimension that reveals covert amplification. Without D3, an admitted set of 20 sources all citing one founder would score high on D1-D2-D4-D5 yet represent 1 effective voice. D3 exists specifically to prevent this failure mode.

## Anti-sycophancy interaction

If the user-preferred source scores D3 = 1 (amplification) but has high D4 Admiralty, do NOT relax D3. The anti-sycophancy NEVER rule (SKILL.md Rule 6) prohibits threshold relaxation based on user preference. Document the user preference in the rationale; score D3 on the metrics.

## Per-discipline recalibration triggers

Phase 9 evaluation must recalibrate thresholds per discipline if:
- In a discipline, BC >= 0.25 is routine (shared-reference-set artifact of small field) -- raise the threshold.
- In a discipline, BC < 0.10 is rare even for genuinely independent work (due to canonical references) -- lower the threshold.

Until per-discipline calibration exists, the thresholds above are the default. Document any manual adjustment in the D3 rationale.

## Output passed to Step 4

```
D3_rationale = {
  bibliographic_coupling_score_vs_admitted_set: <float>,
  amplification_class: "<original-data | amplification | invention>",
  founder_concentration: <float>,
  ancestor_overlap_depth3: <int>,
  community_modularity_Q: <float>,
  coauthor_distance_min: <int>,
  shared_funder_flag: <bool>,
  D3_score: <0-5>,
  set_level_note: "..."   // populated in Step 8
}
```
