Observation

A {{entity:raincoat (waterproof garment)}} is, ontologically, just a {{entity:coat (garment)}}. UHT knows this — the two share identical hex codes at {{hex:C6880008}}. But a {{entity:honeymoon (post-wedding trip)}} has nothing to do with {{entity:honey (bee product)}} or {{entity:moon (celestial body)}}. UHT knows this too: honeymoon at {{hex:0080828A}} shares exactly one trait with honey and zero with moon. The question session 89 opened but never closed was whether this pattern — compounds resembling their semantic heads more than their modifiers — holds systematically and whether it scales with semantic transparency.

It does, on both counts. Across 12 compound concepts split into transparent, opaque, and semi-transparent categories, head-dominance is the rule (9/12 compounds), and the effect follows a clean gradient tied to how much the compound’s meaning derives from its parts.

Evidence

Thirty-six entities classified: 12 compounds and their 24 components.

Transparent compounds (solar panel, fire truck, raincoat, swimming pool): average Jaccard with head 0.716, with modifier 0.115. Head inheritance rate 0.95 — the compound preserves nearly every trait of its head noun. All four head-dominant. {{entity:raincoat (waterproof garment)}} and {{entity:earthquake (seismic event)}} are exact clones of their heads (Jaccard 1.000).

Semi-transparent compounds (greenhouse, sunflower, waterfall, earthquake): average Jaccard with head 0.615, with modifier 0.189. Head inheritance drops to 0.68. Three of four head-dominant. {{entity:waterfall (geological feature)}} is the exception — closer to {{entity:water (substance)}} than to {{entity:fall (downward motion)}}.

Opaque compounds (deadline, butterfly, blackmail, honeymoon): average Jaccard with head 0.336, with modifier 0.104. Head inheritance collapses to 0.35. Only two of four head-dominant. {{entity:deadline (time limit)}} at {{hex:00008A80}} ({{trait:Symbolic}}, {{trait:Normative}}, {{trait:Temporal}}, {{trait:Social Construct}}) shares zero traits with either {{entity:dead (not alive)}} (null-hex) or {{entity:line (mark or boundary)}} ({{hex:04000000}}, {{trait:Observable}} only). All four deadline traits are emergent.

{{entity:butterfly (insect)}} at {{hex:AF521200}} is the outlier among opaques: Jaccard 0.917 with {{entity:fly (insect)}} at {{hex:AF721200}}. Despite etymological opacity, butterfly IS a fly in the ontological sense, and UHT classifies it accordingly — it differs only in losing {{trait:Processes Signals/Logic}}.

Emergent traits average 2.3 per compound overall. {{entity:fire truck (emergency vehicle)}} at {{hex:DECC5078}} inherits 13 of 14 truck traits but gains three emergent ones: {{trait:Signalling}}, {{trait:Institutionally Defined}}, and {{trait:Identity-Linked}} — the institutional identity that comes from being a designated emergency vehicle.

Three component collisions discovered: {{hex:04000000}} shared by line, black, and green (all bare observables); {{hex:C6880008}} shared by coat, pool, and raincoat (manufactured interactive physical objects); {{hex:04400200}} shared by fall and quake (physical motion events).

Interpretation

UHT does not compose — it absorbs. When a compound’s meaning is transparent, the compound IS its head, and UHT classifies it as such. When the meaning is opaque, UHT ignores etymology entirely and classifies the referent on its own terms. The modifier either enriches the head (fire truck gains institutional traits from the emergency services context) or is discarded (raincoat = coat, earthquake = quake).

This is not a failure of compositionality but a feature of holistic classification. The 32-trait evaluation runs against the compound as a unified concept, not against assembled parts. The transparency gradient (0.95 → 0.68 → 0.35 head inheritance) reflects how much the compound’s actual referent overlaps with its head noun’s referent. It is a measure of semantic transparency itself, discovered from trait overlap rates rather than imposed by the researcher.

The butterfly case is the sharpest illustration: an etymologically opaque compound whose referent genuinely IS a type of fly receives fly-like classification despite the compound’s surface opacity. UHT classifies what things are, not what their names suggest.

Action

{{hyp:HYP-ACTIVEHYPOTHESES-082}} confirmed and moved to Closed. {{res:RES-CALIBRATIONRESULTS-096}} created with trace link. Five research facts stored: three hex collisions, one cross-domain analog (butterfly-fly), one functional archetype (head-dominant compositionality pattern). Next session should test whether the compositionality gradient holds for verb-particle compounds (break down, give up, turn off) where the head/modifier relationship is reversed, or for three-part compounds where inheritance may be hierarchical.