Mereology / Parthood / Aggregate

Local identifier: xwkont:concept:mereology-parthood-aggregate Slug: mereology-parthood-aggregate Editorial status: reviewed Created: 2026-07-04 Modified: 2026-07-06

Scope Note

Selection rationale (per ADR-0018's admission bar): Mereology / Parthood / Aggregate is the seventh concept drafted from the 0.2.0 batch. Direct primary-source verification this session found a nameable "aggregate/no-unity" category in 4 of 8 sources (BFO fiat object part/object aggregate, DOLCE arbitrary-sum, SUMO Collection, UFO Collective) — the same source count TODO.md's seed claimed, but with one substitution: YAMATO's claimed non-unitary term was not found anywhere in the fetchable 2010 technical report (see Uncertainty), while UFO's Collective — not in the original seed — was found to be a strong, directly quotable correspondence. GFO, TUpper, and GUM were confirmed to have no reified aggregate/collection entity class, though TUpper does contribute the parthood relations (spatial_part, physical_part) already documented in space.md.

This crosswalk compares each source ontology's own treatment of pluralities and mass-like wholes that lack the unity criterion of an Object/kind-instance — an arbitrary or criterion-bound sum of parts, as distinct from Object (already reviewed, which covers unified wholes) and from Quantity/Amount of Matter (already drafted, quantity-amount-of-matter.md, which covers homeomerous stuff rather than pluralities of discrete members). Sources compared: BFO, DOLCE, SUMO, UFO, GFO, YAMATO, TUpper, GUM (per ADR-0015's 8-source scope).

Cross-cutting finding, established this session: the four sources with a genuine aggregate/collection category split into two sub-patterns by how strict their unity criterion is. BFO's object aggregate and UFO's Collective both require member parts to play a uniform role with respect to the whole (BFO: "a plurality... as member parts which together form a unit"; UFO: "parts play the same role with respect to the whole, e.g., the Black Forest as a collective of trees"). DOLCE's arbitrary-sum and, more loosely, SUMO's Collection instead allow a genuinely unrestricted, criterion-free sum (DOLCE: "the mereological sum of any two or more endurants... no unity criterion... 'extensional'"; SUMO: "members can be added and subtracted without thereby changing the identity of the Collection"). BFO additionally supplies a second, structurally distinct category with no counterpart in any other source checked — fiat object part, a sub-object part demarcated by a fiat (not natural) boundary, which is about dividing a unified whole rather than summing discrete members. See note-001, note-002.

Exclusions: this crosswalk does not address Boundary/Site (a separate 0.2.0-batch candidate; BFO's fiat object part and its demarcating "fiat surfaces" are directly relevant background for that future crosswalk, not resolved here) or Object (already reviewed; the Object/Aggregate contrast that BFO's, SUMO's, and UFO's own documentation each draw is noted but not re-litigated).

Core.ttl placement is deliberately left open at this draft stage — see Uncertainty.

Labels, Alternate Labels, and Source Terminology

Role	Label or term	Source	Language	Notes
XwkOnt working label	Mereology / Parthood / Aggregate	XwkOnt	en	Not yet in data/ontology/core.ttl — see Scope Note.
Source term	Object aggregate (+ Fiat object part)	BFO	en	Two structurally distinct categories: a plurality-summing one and a whole-dividing one, both subtypes of material entity.
Source term	Arbitrary-sum	DOLCE	en	AKA "arbitrary-collection"; a mereological sum with no unity criterion, disjoint from both physical- and non-physical-endurant.
Source term	Collection	SUMO	en	A Physical subclass, disjoint from SelfConnectedObject; members can change without changing the Collection's identity.
Source term	Collective	UFO	en	One of three leaf partition members of Substantial (alongside Object, Quantity, per quantity-amount-of-matter.md's own UFO findings).
Alternate label	(no aggregate/collection class — see Uncertainty)	GFO	en	"Collection" occurs only informally inside Configuration's own gloss (already documented in situation-state-of-affairs.md), not as its own class.
Alternate label	Non-unitary (claimed in TODO.md's seed, not found — see Uncertainty)	YAMATO	en	The literal term "non-unitary" does not occur anywhere in the fetchable 2010 technical report; related but distinct discussion of process/event "unity" exists on the occurrent side only.
Alternate label	(relations only, no aggregate entity class — see Uncertainty)	TUpper	en	spatial_part/physical_part/spatial_C/physical_C (already documented in space.md) are parthood/connection relations, not a reified Aggregate/Collection class.
Alternate label	(no class — see Uncertainty)	GUM	en	Zero occurrences of "Aggregate," "Collection," "Collective," or "Sum" as defined GUM classes.

Source Definitions and Contextual Notes

Source	Term or identifier	Dimension	Claim type	Definition, quotation, or paraphrase	Reference	Locator	Notes
BFO	Object aggregate (BFO_0000027)	technical	direct quotation	"(Elucidation) An object aggregate is a material entity consisting exactly of a plurality (≥1) of objects as member parts which together form a unit." Example: "The aggregate of the musicians in a symphony orchestra and their instruments; the aggregate of bearings in a constant velocity axle joint; the nitrogen atoms in the atmosphere; a collection of cells in a blood biobank." rdfs:subClassOf material entity (BFO_0000040). dc11:identifier "025-BFO".	xwkont:ref:bfo-2020	verified: bfo-core.ttl, class BFO_0000027, fetched and read directly 2026-07-04	BFO's own scope note (already noted when time.md/space.md fetched this same region of the file) clarifies "exactly" excludes any parts beyond the member parts, and that the plurality can transiently shrink to one member while still counting as the same aggregate.
BFO	Fiat object part (BFO_0000024)	technical	direct quotation	"(Elucidation) A fiat object part b is a material entity & such that if b exists then it is continuant part of some object c & demarcated from the remainder of c by one or more fiat surfaces." Example: "The upper and lower lobes of the left lung; the dorsal and ventral surfaces of the body; the Western hemisphere of the Earth." rdfs:subClassOf material entity (BFO_0000040). dc11:identifier "027-BFO".	xwkont:ref:bfo-2020	verified: bfo-core.ttl, class BFO_0000024, fetched and read directly 2026-07-04	A structurally distinct category from object aggregate — this one divides a unified whole via non-natural (fiat) boundaries rather than summing discrete members. No counterpart to this specific division-not-summation category was found in any other of the 8 sources — see note-002.
DOLCE	Arbitrary-sum	technical	direct quotation	"AKA arbitrary-collection. The mereological sum of any two or more endurants (physical or not). Arbitrary sums have no unity criterion (they are 'extensional')." rdfs:subClassOf endurant; owl:disjointWith physical-endurant, owl:disjointWith non-physical-endurant.	xwkont:ref:dolce-lite-owl	verified: DOLCE-Lite.owl, class #arbitrary-sum, fetched and read directly 2026-07-04	The most permissive of the four correspondences — any sum of two or more endurants qualifies, with no member-role-uniformity requirement, unlike BFO's object aggregate or UFO's Collective. Disjoint from both physical- and non-physical-endurant, i.e. a third, orthogonal endurant category alongside those two branches.
SUMO	Collection	technical	direct quotation	"Collections have members like Classes, but, unlike Classes, they have a position in space-time and members can be added and subtracted without thereby changing the identity of the Collection. Some examples are toolkits, repeated actions, football teams, and flocks of sheep." (subclass Collection Physical); (disjoint Collection SelfConnectedObject).	xwkont:ref:sumo-niles-pease-2001	verified: current Merge.kif, fetched and read directly 2026-07-04	SUMO's own documentation explicitly contrasts Collection with Class (already crosswalked in universal-type.md as SUMO's Abstract-side classifier) — a Collection is Physical, has spatiotemporal location, and tolerates membership change without identity change, the opposite of a Class's intensional, condition-defined membership.
UFO	Collective	technical	direct quotation	"Collectives are entities whose parts play the same role with respect to the whole, e.g., the Black Forest (as a collective of trees), a deck of cards, the Dutch-speaking group in the crowd." Contrasted in the same passage with Quantities ("maximally-topologically-self-connected... homeomerous amounts of matter") and Objects ("aka functional complexes... parts play differentiated functional roles"). One of three partition members of Substantial.	xwkont:ref:ufo-2021	verified: 2021 Applied Ontology paper, already-extracted text re-searched directly 2026-07-04	Not part of TODO.md's original seed for this concept — a genuine addition. UFO's own three-way Substantial partition (Object/Collective/Quantity) directly parallels this crosswalk's own three-concept adjacency (Object, this concept, Quantity/Amount of Matter, per quantity-amount-of-matter.md) — the cleanest structural fit of any source to XwkOnt's own concept boundaries.
GFO	(no aggregate/collection class found)	technical	non-equivalence	Full-text grep of modules/gfo-base.owl for "aggregate," "mereolog," "sum" (as a class name), and "heap" returned zero class declarations; the sole "collection" hits are XML/RDF rdf:parseType="Collection" syntax (unrelated) and Configuration's own informal gloss ("we consider a collection of presential facts," already documented in situation-state-of-affairs.md).	xwkont:ref:gfo	verified absence: modules/gfo-base.owl, fetched and read directly 2026-07-04	Not part of TODO.md's original seed for this concept; checked directly for completeness. This is the second 0.2.0-batch concept (after Situation/State of Affairs) where GFO's usual pattern of contributing a formally exhaustive top-level category does not hold — GFO has no counterpart at all here.
YAMATO	(claimed term "non-unitary" not found; related but distinct occurrent-side discussion exists)	philosophical	non-equivalence	Full-text search of the extracted YAMATO 2010 technical report for "non-unitary," "nonunitary," and "non unitary" (case-insensitive) returned zero matches. The document does discuss unity in a related but distinct, occurrent-side sense: "Processes are dissective and hence they have no unity. It has no whole, and hence it has no (temporal) part... an event exists with unity in the temporal space, that is, it must be always viewed as a whole."	xwkont:ref:yamato-mizoguchi-2010	verified absence of the claimed term; distinct related content found: 2010 technical report, full extracted text re-searched directly 2026-07-04	TODO.md's seed claim is not supported by the one fetchable YAMATO primary document — this may be a term from YAMATO's OWL/Hozo files (still registration-gated, per the same limitation already noted for Time/Space/Abstract) or the blocked 2022 paper, not the 2010 report. The unity discussion that does exist in this document concerns process/event dissectiveness (an occurrent-side, temporal-parts question, already adjacent to event.md/process.md), not an endurant-side aggregate/plurality category — a different question from this concept's own scope.
TUpper	(mereotopology relations only, no aggregate entity class)	technical	non-equivalence	spatial_part/spatial_C and physical_part/physical_C (already quoted in full in space.md's Source Definitions) define parthood and connection relations over spatial regions and physical bodies respectively — no separate Aggregate, Collection, or Sum predicate/class is declared anywhere in TUpper-Terms.html.	xwkont:ref:tupper-colore	verified absence of an entity class; relations confirmed: TUpper-Terms.html, fetched and read directly 2026-07-04	TUpper formalizes parthood as a relation thoroughly (a full mereotopology, per space.md) but never reifies "the sum/aggregate of some parts" as its own kind of thing — a structurally different modeling choice from BFO's/DOLCE's/SUMO's/UFO's entity-class approach.
GUM	(no class found)	technical	non-equivalence	Full-text grep of GUM-31.owl for #Aggregate, #Collection, #Collective, #Sum, and #Group (GUM's own PascalCase convention) returned zero matches.	xwkont:ref:gum-owl	verified absence: GUM-31.owl, fetched and read directly 2026-07-04	The third 0.2.0-batch concept (after Situation/State of Affairs and Universal/Type) where GUM contributes nothing previously uncredited.

Source Ontology Correspondences

Correspondence ID	Source ontology	Source term	Source identifier or IRI	Source version	Reference	Inclusion rationale
xwkont:correspondence:mereology-parthood-aggregate:001	BFO	Object aggregate (+ Fiat object part)	BFO_0000027, BFO_0000024	BFO 2020 (directly verified 2026-07-04)	xwkont:ref:bfo-2020	Direct terminological match; two structurally distinct sub-categories, both material entities.
xwkont:correspondence:mereology-parthood-aggregate:002	DOLCE	Arbitrary-sum	http://www.loa-cnr.it/ontologies/DOLCE-Lite.owl#arbitrary-sum	DOLCE-Lite v397 (directly verified 2026-07-04)	xwkont:ref:dolce-lite-owl	Direct terminological match; the most permissive (criterion-free) of the four correspondences.
xwkont:correspondence:mereology-parthood-aggregate:003	SUMO	Collection	Collection (SUMO term names are their own identifiers)	Current Merge.kif (directly verified 2026-07-04)	xwkont:ref:sumo-niles-pease-2001	Direct terminological match; explicitly contrasted with SUMO's own Class in the same documentation passage.
xwkont:correspondence:mereology-parthood-aggregate:004	UFO	Collective	not applicable — no IRI scheme in the 2021 paper itself	Applied Ontology, 2021 (directly re-verified 2026-07-04)	xwkont:ref:ufo-2021	Direct terminological match; a leaf partition member of Substantial, requiring member-role uniformity, closer in spirit to BFO's object aggregate than to DOLCE's/SUMO's more permissive categories.

No GFO, YAMATO, TUpper, or GUM correspondence is recorded — see Source Definitions and Uncertainty.

Semantic Comparison Notes

Note ID	Dimension	Claim type	Note	Supporting references	Confidence
note-001	philosophical	editorial observation	The four confirmed sources split into two unity-strictness sub-patterns. BFO's object aggregate and UFO's Collective both require member parts to play a uniform role with respect to the whole — BFO: "a plurality... as member parts which together form a unit"; UFO: "parts play the same role with respect to the whole." DOLCE's arbitrary-sum and SUMO's Collection instead permit a genuinely unrestricted sum — DOLCE explicitly states arbitrary sums "have no unity criterion (they are 'extensional')"; SUMO's own documentation allows "members [to] be added and subtracted without thereby changing the identity of the Collection." This is a real, citable difference in how strict a "no full Object-unity" category is allowed to be, not just a naming variation — worth preserving as two distinguishable sub-senses rather than collapsing all four into one undifferentiated correspondence.	xwkont:ref:bfo-2020, xwkont:ref:ufo-2021, xwkont:ref:dolce-lite-owl, xwkont:ref:sumo-niles-pease-2001	high
note-002	technical	editorial observation	BFO's fiat object part has no counterpart in any of the other 7 sources checked — it is about dividing an already-unified whole via non-natural (fiat) boundaries ("demarcated from the remainder of c by one or more fiat surfaces"), the structural opposite of summing discrete, separately-existing members into a plurality. This is directly relevant background for the planned Boundary/Site crosswalk (TODO.md's 0.2.0 batch item 8), which will cover BFO's fiat-boundary apparatus (continuant fiat boundary, fiat point/line/surface) in its own right.	xwkont:ref:bfo-2020	high
note-003	technical	editorial observation	UFO's Substantial partition (Object/Collective/Quantity) maps onto XwkOnt's own concept boundaries more cleanly than any other source's treatment across the three related 0.2.0-batch concepts touching this territory (Object, already reviewed; this concept; Quantity/Amount of Matter, quantity-amount-of-matter.md) — UFO draws exactly the same three-way distinction XwkOnt's own crosswalk scoping already does, while BFO, DOLCE, and SUMO each split the same territory differently (e.g. DOLCE's arbitrary-sum cuts across both physical and non-physical endurants, unlike UFO's Collective, which — like Object and Quantity — is a Substantial, i.e. implicitly physical/concrete).	xwkont:ref:ufo-2021	high

Mapping Assertions or Candidate Relations

Mapping ID	Subject	Relation category	Object	predicate_id	mapping_justification	Status	Confidence	Rationale	Provenance
xwkont:mapping:mereology-parthood-aggregate:001	BFO:Object aggregate	close-match	UFO:Collective	skos:closeMatch	semapv:ManualMappingCuration	candidate	high	Both require member parts to play a uniform role with respect to the whole (BFO: "form a unit"; UFO: "play the same role with respect to the whole"), and both give near-identical worked examples (BFO: "aggregate of the musicians in a symphony orchestra"; UFO: "Black Forest as a collective of trees"). The closest structural pairing in this crosswalk.	xwkont:ref:bfo-2020, xwkont:ref:ufo-2021
xwkont:mapping:mereology-parthood-aggregate:002	DOLCE:Arbitrary-sum	close-match	SUMO:Collection	skos:closeMatch	semapv:ManualMappingCuration	candidate	high	Both permit a criterion-free, membership-changeable sum — DOLCE's "no unity criterion... extensional" and SUMO's "members can be added and subtracted without thereby changing the identity" describe the same permissive pattern. DOLCE's own framing (mereological sum, "extensional") and SUMO's (spacetime-located, Class-contrasted) emphasize different aspects of the same underlying idea — a confidently-identified nuance in framing, directly evidenced by each source's own text, not an open sourcing question.	xwkont:ref:dolce-lite-owl, xwkont:ref:sumo-niles-pease-2001
xwkont:mapping:mereology-parthood-aggregate:003	BFO:Object aggregate	overlap	DOLCE:Arbitrary-sum	none	semapv:ManualMappingCuration	candidate	medium	Both are pluralities of endurant/material-entity-side parts, but BFO's requires member-role uniformity ("form a unit") while DOLCE's explicitly does not ("no unity criterion") — a genuine strictness divergence per note-001, hence overlap rather than close-match.	xwkont:ref:bfo-2020, xwkont:ref:dolce-lite-owl
xwkont:mapping:mereology-parthood-aggregate:004	UFO:Collective	overlap	SUMO:Collection	none	semapv:ManualMappingCuration	candidate	medium	Same strictness divergence as mapping-003 — UFO requires uniform member roles; SUMO explicitly allows membership change without identity change, a looser criterion.	xwkont:ref:ufo-2021, xwkont:ref:sumo-niles-pease-2001
xwkont:mapping:mereology-parthood-aggregate:005	BFO:Fiat object part	unknown	(no counterpart in any other of the 8 sources)	none	semapv:ManualMappingCuration	candidate	low	Recorded explicitly as a genuine BFO-only category, not silently dropped — see note-002. Directly relevant to the planned Boundary/Site crosswalk.	xwkont:ref:bfo-2020
xwkont:mapping:mereology-parthood-aggregate:006	xwkont-core:Aggregate (candidate)	unknown	GFO	none	semapv:ManualMappingCuration	candidate	low	No GFO correspondence identified; zero class declarations for "aggregate"/"mereolog"/"sum"/"heap" anywhere in modules/gfo-base.owl.	xwkont:ref:gfo
xwkont:mapping:mereology-parthood-aggregate:007	xwkont-core:Aggregate (candidate)	unknown	YAMATO	none	semapv:ManualMappingCuration	candidate	low	No YAMATO correspondence identified; TODO.md's seed claim ("non-unitary") was not found anywhere in the fetchable 2010 technical report — see Uncertainty.	xwkont:ref:yamato-mizoguchi-2010
xwkont:mapping:mereology-parthood-aggregate:008	xwkont-core:Aggregate (candidate)	unknown	TUpper	none	semapv:ManualMappingCuration	candidate	low	No reified TUpper correspondence identified; spatial_part/physical_part are relations, not an aggregate entity class.	xwkont:ref:tupper-colore
xwkont:mapping:mereology-parthood-aggregate:009	xwkont-core:Aggregate (candidate)	unknown	GUM	none	semapv:ManualMappingCuration	candidate	low	No GUM correspondence identified; zero occurrences of "Aggregate"/"Collection"/"Collective"/"Sum" as defined GUM classes.	xwkont:ref:gum-owl

Uncertainty, Non-Equivalence, and Open Questions

Item ID	Type	Description	Impact	Follow-up
uncertainty-001	non-equivalence	TODO.md's seed claimed "YAMATO (non-unitary)" as a correspondence for this concept. Direct full-text search of the one fetchable YAMATO primary document (the 2010 technical report) found zero occurrences of "non-unitary"/"nonunitary"/"non unitary." A related but distinct discussion of process/event "unity" exists in the same document, but on the occurrent (temporal-parts) side, not as an endurant-side aggregate/plurality category.	TODO.md's seed for this concept is not fully supported by the fetchable primary source; no YAMATO correspondence is recorded in this crosswalk.	Re-check if YAMATO's OWL/Hozo files (still registration-gated) or the blocked 2022 paper become accessible — "non-unitary" may be a term from one of those, not the 2010 report.
uncertainty-002	open-question	Where should xwkont-core:Aggregate subclass from once added to data/ontology/core.ttl? BFO and UFO both treat this as a material/substantial-side category with a uniform-member-role criterion; DOLCE and SUMO treat it more permissively and, in DOLCE's case, deliberately orthogonal to the physical/non-physical split. Recommendation recorded 2026-07-04, in response to external review: model both sub-patterns explicitly as two sibling sub-concepts rather than one undifferentiated Aggregate class — a strict, uniform-member-role Aggregate (BFO object aggregate/UFO Collective) and a permissive, criterion-free Sum (DOLCE arbitrary-sum/SUMO Collection) — because note-001 establishes this is a real, citable strictness difference across all four confirmed sources (2 sources per pattern, an even split, not a majority/minority case that would justify picking one and treating the other as a variant). This mirrors the same two-sub-concept resolution recorded for boundary-site.md's own uncertainty-001 (part-of-host boundary vs. not-part-of-host dependent place) — both are cases where this batch's own evidence splits evenly rather than converging on one class.	Blocks final core.ttl placement; does not block continuing this crosswalk's research/review. Recorded recommendation resolves the "decide whether to model strict aggregate vs. permissive sum separately" item flagged by the 2026-07-04 external review.	Confirm or override this recommendation at review time.
uncertainty-003	open-question	BFO's fiat object part (note-002) has no counterpart in this crosswalk's other 7 sources and is more directly relevant to the planned Boundary/Site crosswalk than to this one. Whether it should be cross-referenced there instead of (or in addition to) here is a scoping question for that future crosswalk.	Does not block this crosswalk's own completion; a forward-looking scoping note for Boundary/Site.	Cross-check BFO's fiat object part/continuant fiat boundary apparatus explicitly when drafting the Boundary/Site crosswalk next.

Provenance and References

• xwkont:ref:bfo-2020 — Basic Formal Ontology (BFO) 2020 / ISO/IEC 21838-2:2021 — verified directly against bfo-core.ttl, 2026-07-04
• xwkont:ref:dolce-lite-owl — DOLCE-Lite OWL translation — verified directly against DOLCE-Lite.owl, 2026-07-04
• xwkont:ref:sumo-niles-pease-2001 — Towards a Standard Upper Ontology (Niles & Pease, 2001) — verified directly against current SUMO Merge.kif, 2026-07-04
• xwkont:ref:ufo-2021 — UFO: Unified Foundational Ontology (Guizzardi et al., 2021) — verified directly (full-text re-search), 2026-07-04
• xwkont:ref:gfo — General Formal Ontology (GFO) — verified absence directly against modules/gfo-base.owl, 2026-07-04
• xwkont:ref:yamato-mizoguchi-2010 — YAMATO 2010 technical report (Mizoguchi) — verified absence of claimed term directly against the extracted PDF, 2026-07-04
• xwkont:ref:tupper-colore — TUpper COLORE formalization (Grüninger) — verified absence of entity class; relations confirmed directly against TUpper-Terms.html, 2026-07-04
• xwkont:ref:gum-owl — GUM 3.1 OWL (Bateman) — verified absence directly against GUM-31.owl, 2026-07-04

Review History

Review ID	Date	Outcome	Notes
—	2026-07-04	Not yet reviewed — draft	Seventh concept of the 0.2.0 batch (ADR-0018), following time.md through universal-type.md. All 8 sources checked directly against primary artifacts already cached from prior crosswalks' research. Matches TODO.md's 4-source seed count, but with one substitution: YAMATO's claimed "non-unitary" term was not found in the fetchable primary document, while UFO's Collective (not in the seed) was found to be a strong, directly quotable correspondence, and maps onto XwkOnt's own Object/Aggregate/Quantity concept boundaries more cleanly than any other source (note-003). Found two sub-patterns of unity-strictness across the four confirmed sources (note-001) and one BFO-only category (fiat object part, note-002) directly relevant to the next crosswalk in the batch. Pending maintainer review before advancing to reviewed.
xwkont:review:mereology-parthood-aggregate:2026-07-05:01	2026-07-05	Passed — advanced draft → reviewed	Checked against docs/governance/contributing.md's Review Checklist: scope preserved; every xwkont:ref:* citation resolves; correspondence/mapping/note/uncertainty ID numbering sequential (correspondences 001-004, mappings 001-009, notes 001-003, uncertainty 001-003); all confidence values within the ADR-0013 vocabulary. Correction (2026-07-06, full-corpus audit): this entry originally claimed "the medium-high mapping/note state their sourcing rationale" — false on inspection: note-003 and mapping-002 both used medium-high with substantive/evidentiary rationales (a cleaner conceptual fit; different framing emphasis), not a sourcing-change justification. Both raised to high confidence in this pass — each finding is directly evidenced, not an open sourcing question. See docs/methodology/crosswalk-runbook.md's governing principle. The YAMATO seed correction ("non-unitary" not found) confirmed consistently reflected in Source Definitions and uncertainty-001. Confirmed the uncertainty-002 two-sub-concept recommendation: Aggregate (strict, uniform-member-role — BFO/UFO) and Sum (permissive, criterion-free — DOLCE/SUMO) will be modeled as sibling sub-concepts, on the strength of the even 2/2 source split documented in note-001 — not a majority/minority case. This confirmation is a recorded modeling decision, not a core.ttl edit; that Turtle-change work (which now needs to add two sibling classes, not one) remains separately tracked, consistent with boundary-site.md's analogous two-sub-concept call. Self-review, not independent third-party review.

Future Work

• ~~Confirm or override the uncertainty-002 two-sub-concept recommendation~~ — done 2026-07-05: confirmed (xwkont:review:mereology-parthood-aggregate:2026-07-05:01); advanced draft → reviewed. The core.ttl addition of both sibling classes remains separately-tracked Turtle-change work.
• Re-check YAMATO's OWL/Hozo files or the blocked 2022 paper for the seed's claimed "non-unitary" term (uncertainty-001), if either becomes accessible.
• ~~Create the Boundary/Site crosswalk next~~ Done — boundary-site.md and the rest of the 0.2.0 batch are now drafted; see its own note-002/uncertainty-003 for the BFO fiat object part/continuant fiat boundary cross-reference.