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Wikidata:Property proposal/has surface

< Wikidata:Property proposal

has surface

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Originally proposed at Wikidata:Property proposal/Generic

   Done: has surface (P10614) (Talk and documentation)
Descriptionthe object is the 2-dimensional surface that partly or completely surrounds the subject in 3-dimensional space
Data typeItem
Example 1deltoid muscle (Q130243) → surface of deltoid (Q66591974)
Example 2liver (Q9368) → surface of liver (Q66509673)
Example 3organ (Q712378) → surface of organ (Q66515789)
See alsohas boundary (P4777)

Motivation

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We currently have no way to model the relationship between deltoid muscle (Q130243) and surface of deltoid (Q66591974) ChristianKl ❪✉❫ 19:38, 6 December 2020 (UTC)[reply]

ChristianKl (talk) 14:41, 8 July 2016 (UTC) Iwan.Aucamp (talk) 15:13, 22 March 2020 (UTC) Was a bee (talk) 14:48, 23 September 2017 (UTC) Okkn (talk) 02:20, 25 October 2017 (UTC) JS (talk) Heihaheihaha (talk) 12:31, 8 January 2024 (UTC)[reply]

  Notified participants of WikiProject Anatomy

Discussion

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  Notified participants of WikiProject Mathematics ChristianKl ❪✉❫ 19:49, 7 December 2020 (UTC)[reply]

  •   Support --Tinker Bell ★ ♥ 19:37, 7 December 2020 (UTC)[reply]
  • I talked with a friend who's a mathematician and now I specified it a bit better. Additionally, I made it explicit that sometimes the surface is not completely surrounding for cases like the surface of the heart that gets pierced by an artery/vein. ChristianKl ❪✉❫ 18:20, 8 December 2020 (UTC)[reply]
  • I switched it to be more open for surfaces that don't completely surround the object. ChristianKl ❪✉❫ 18:09, 10 December 2020 (UTC)[reply]
  •   Oppose How is the proposed property different than has boundary (P4777)? If we want to create a new property specifically for biological items, I'm fine with that, but in mathematical items we should use has boundary (P4777). As far as the mathematical definition of a surface, we define a surface as a two-dimensional space. A surface, however, can be embedded in higher dimensional spaces. So, a sphere is two-dimensional because if you zoom in on the surface it has no thickness--it looks like a 2D plane. We often represent a sphere in three dimensions, however. But we could also put it in four-dimensional space, five-dimensional space, etc. — The Erinaceous One 🦔 09:26, 14 December 2020 (UTC)[reply]
@The-erinaceous-one: has boundary (P4777) was created with idea that it's what you get when you project a 3D entity on a 2D plane. It's intented to be the relationship between Walls of Jerusalem (Q2918723) and Old City of Bones (Q213274). ChristianKl ❪✉❫ 12:47, 14 December 2020 (UTC)[reply]
@ChristianKl: I see. The mathematical definition of "boundary" is much broader than the meaning of has boundary (P4777) that you described because the boundary of an object can n-dimensional with n >= 0 (depending on the object). Semantically, I've never heard anybody say "a <mathematical object> has surface <x>" so it doesn't make sense to try to shoehorn mathematical objects into the proposed property. I would much rather broaden the definition of has boundary (P4777) to allow for mathematical objects in more than two dimensions. — The Erinaceous One 🦔 00:43, 23 December 2020 (UTC)[reply]
@The-erinaceous-one: For objects in the physical world there's a massive difference between being surrounded when you project into 2D and being surrounded in 3D and it doesn't really make sense to model them with the same relation. ChristianKl ❪✉❫ 01:35, 23 December 2020 (UTC)[reply]
@ChristianKl: I just don't see the number of dimensions as a quality that merits a new property. There are four dimensional objects that have boundaries too. Would we need another new property? In fact, on hyperball (Q3776995) there is the statement: hyperball (Q3776995)has boundary (P4777)n-sphere (Q306610). This means that different instances Q3776995 will have boundaries of various dimensions. How would you propose modeling this? — The Erinaceous One 🦔 12:04, 23 December 2020 (UTC)[reply]
Given the current definition of has boundary (P4777) that comes from it's property discussion hyperball (Q3776995)has boundary (P4777)n-sphere (Q306610) is clearly wrong.
The relationship between cell (Q7868) → cell surface (Q189094) is not the same as the one between Walls of Jerusalem (Q2918723) → Walls of Jerusalem (Q2918723). Both cell (Q7868) and Walls of Jerusalem (Q2918723) happen to be items that exist in 3D reality, so it's not possible to unambiguously interfer which meaning is intended when the same property is used. ChristianKl ❪✉❫ 20:42, 23 December 2020 (UTC)[reply]
@ChristianKl: I think we need reconsider the details of has boundary (P4777). The current description is unclear. The first part says, "element that's on the two dimensional border that surrounds the subject," but the second part says, "the limit of an entity." The meaning of the two parts, together, is ambiguious. The first part states a narrower usage of "has boundary" you described, whereas the second part indicates a broader usage that is in line with the mathematical usage of the "boudary." Additionally, in the has boundary (P4777) property proposal, there wasn't discussion regarding the dimension of the boundary; you mention it once, but nobody else commented on it before the property was created. In other words, there wasn't a consensus at the time that "has boundary" only applies to 2D objects with a 1D boundary (or a 2D projection of a 3D object). (Side note: if we determine P4777 should only apply to a border in a 2D projection, then the description should say, "element on the one-dimensional border that surrounds the subject," since a curve in a plane is a one-dimensional obejct.)
If we go with the narrow meaing of P4777 then I have two concerns. The first is that it destroys its utiltiy as a mathematical property. Replacing it with "has surface" is better than nothing but it is contrary to the semantics used within mathematics. Secondly, I am concerned about restricting has boundary (P4777) to only the 2D case causes the property to arbitrarily include some types of political/legal boundaries and exclude other types. In particular, consider a fictional Sci-Fi universe with boundaries between nations "X" and "Y" in outer space. The "X-Y boundary" would be a 2D boundary in 3D space and the relationship between "X" and "X-Y boundary" is exactly the same as the relationship between "the US" and the "US-Mexico border." Similar cases also arise in the real world when you consider the vertical boundaries of a piece of property or nation [1]. Allowing P4777 to use the broader meaning would increase its usefulness without requiring a proliferation of properties.
Regarding the ambiguity you mentioned, I don't see this being a real source of confusion (for humans). It is usually clear when we talk about the boundary of a geographic item, we are talking about the boundary of the projection on the map. If it's not clear, we could make it explicit by adding a qualifier along the lines of United Stateshas borderUS-Mexico borderwith respect tomap projection. — The Erinaceous One 🦔 12:30, 26 December 2020 (UTC)[reply]
I see no reason has boundary (P4777) should be limited to two dimensions. Any body, regardless of the number of dimensions, are limited by another object with one dimension less. This is proved by divergence theorem (Q338886) and Green's theorem (Q321237). /ℇsquilo 14:53, 24 August 2021 (UTC)[reply]
  Support as distinct from has boundary (P4777). 'Chair' > has surface > 'upholstery' seems a lot more reasonable than 'Chair' > has boundary > 'upholstery'. There may be overlap between 'surface' and 'boundary', but they are not wholly equal sets. Josh Baumgartner (talk) 23:50, 28 September 2021 (UTC)[reply]
  Support looks reasonable. TiagoLubiana (talk) 17:04, 21 December 2021 (UTC)[reply]
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