Talk:Q16889133

Confusion between all these "classes"

This item has a property which claims that 'class' (this item) is a subclass (subclass of (P279)) of 'class' (class (Q5127848)). How confusing! Bever (talk) 00:28, 10 March 2015 (UTC)

@Bever: I was not able to locate the original discussion that led to this configuration but from what I recall:

1. top level: the parent class (Q5127848), most general, philosophical concept, described (though not too clearly) at WP:Class (philosophy);
2. second level : this item, class (Q16889133), is the common sense organisation of objects, matching the 1st definition of the wiktionary: "A group, collection, category or set sharing characteristics or attributes."
3. third level : amongst multiple derived entities, item class (Q217594) is the mathematical concept of class / set (definition #11 in wiktionary): "(mathematics) A collection of sets definable by a shared property.", described in Wikidata as a "collection of sets in mathematics that can be defined based on a property of its members"

See also Talk:Q217594. Generally speaking, most classifications should derive from the current item, I believe.

-- LaddΩ chat ;) 22:59, 10 March 2015 (UTC)

синонимы

группа объектов с общими характеристиками - множество (Q36161) --Fractaler (talk) 13:03, 16 August 2016 (UTC)

No. --Infovarius (talk) 19:45, 16 August 2016 (UTC)

Утверждения

1) это частный случай понятия (Property:P31) = 2) подкласс от (Property:P279) = 3) часть от (Property:P361) = 4) подмножество (Q177646) --Fractaler (talk) 13:08, 16 August 2016 (UTC)

No. --Infovarius (talk) 19:45, 16 August 2016 (UTC)

Примеры: деревня (Q5084) - частный случай понятия (Property:P31) типы административно-территориальной единицы = 2) подкласс от (Property:P279) класса типы административно-территориальной единицы = 3) часть от (Property:P361) целого типы административно-территориальной единицы = 4) подмножество (Q177646) множества типы административно-территориальной единицы --Fractaler (talk) 07:21, 17 August 2016 (UTC)

Нет. "типы АТЕ" - это множество из {деревня, область, страна, и т.д.}. "Деревня" является его элементом, и не подмножеством или подклассом. Про элементы множество обычно не говорят "часть". --Infovarius (talk) 20:54, 17 August 2016 (UTC)

Ок, как Вы классифицируете, например, Барвиха (деревня)? --Fractaler (talk) 06:57, 18 August 2016 (UTC)

В чём проблема? "Это" "деревня". Это элемент класса "деревня". --Infovarius (talk) 11:41, 19 August 2016 (UTC)

Проблема - в ограничении (иожно использовать только терминологию теории множеств, без "элемент класса" и т.д.) --Fractaler (talk) 12:56, 19 August 2016 (UTC)

class (Q5127848)

Merge? class (Q5127848): "philosophical term denoting a group of things derived from extensional or intensional definition". class (Q16889133): (ontological philosophical term) "collection of individuals or objects. A class can be defined either by extension, or by intension". --Fractaler (talk) 09:26, 24 November 2017 (UTC)

Merge with group (Q16887380)?

class (Q16889133): "group of items sharing common characteristics". group (Q16887380): "summarizes entities with similar characteristics together". The same. --Fractaler (talk) 09:57, 8 January 2018 (UTC)

The merger is inappropriate; it would have seemed to be appropriate given the previous wrong/unconventional definition of "group"; now that group is defined as "well-defined, enumerable collection of discrete entities that form a collective whole", the distinction between a class and a group is reasonably well maintained even on the definition level. --Dan Polansky (talk) 07:47, 24 June 2023 (UTC)

中文翻译：等级？？

为什么本事物叫“等级”？

“等级”根这概念完全不相同。

type vs class

Hi, am I wrong saying that a class is exactly like a type, but in the specific context of an ontology ? So that "class" should be a subclass of "type" and not the inverse like it is today ? CaLéValab (talk) 02:08, 18 December 2021 (UTC)

@CaLéValab Depends on the « type » definition you chose, but if it’s a type in programming or in math, a type is a collection of abstract mathematical entities. So this (generic) definition of what a class is is more general. author  TomT0m / talk page 11:52, 18 December 2021 (UTC)

Hi @TomT0m: I'm referring to type (Q21146257) which is used for things like type of musical work/composition (Q107487333). CaLéValab (talk) 11:59, 18 December 2021 (UTC)

Actually « type » is a property of the dublin core, not a class, so this is not really relevant at first sight. It’s an equivalent for instance of (P31) here. The item is probably not really well named and linked.

Nethertheless, it seems that the values of this properties are intended to be classes of works. Which makes them actually specific example of classes. If you look at the intended values for this property on the dublin core site, which is https://www.dublincore.org/specifications/dublin-core/dcmi-type-vocabulary/ if I’m right, you’ll notice that they are … classes. For example « collection » is a class.

This is confirmed by the « DCMItype » https://dublincore.org/specifications/dublin-core/dcmi-terms/#DCMIType , which is the real matching url for type (Q21146257), which is defined by « The set of classes specified by the DCMI Type Vocabulary, used to categorize the nature or genre of the resource. ». An example of « DCMIType » is ontologically a class. author  TomT0m / talk page 12:17, 18 December 2021 (UTC)

Class (metaclass) vs group (class of concrete objects)

@Swpb: you merged Q16887380 (group) into this item. That other item was originally intended to be a class of concrete objects, meaning that its instances are non-classes (concrete objects) like Great Lakes (Q7347) (group of five lakes). Whereas instances of class (Q16889133) are other classes (abstract objects) like group of lakes (Q5926864). This is an important distinction, and due to this merge now classes and non-classes are instances of the same class in a messy way. So I believe that separate "group" item should be restored.

I see what may have lead you to merge the group item, though. Namely its basic statements were messed up in its previous version (Special:PermaLink/1862060394). It should not have been set as an instance of metaclass nor as a subclass of class. Similarly several other classes in upper ontology have been messed up (e.g. see Talk:Q16334298#Metaclass, Talk:Q61961344). 2001:7D0:81FD:BC80:8507:95E7:7B4B:8CE1 12:49, 22 May 2023 (UTC)

The statements on Q16887380 (both the old version you linked, and immediately pre-merge) do not imply that its members should be concrete (i.e. having a physical referent, per concrete object (Q4406616), unless you're using some other definition of "concrete"). The uses of Q16887380 don't support that implication either. There is another item with that definition: group of physical objects (Q61961344). Re-defining Q16887380 to mean "group of concrete objects" would a) create redundancy with group of physical objects (Q61961344), and b) leave a lot of incorrect statements on items that are not groups of concrete objects. Furthermore, the difference between Great Lakes (Q7347) and group of lakes (Q5926864) is that the former is an instance of class/group, while the latter is a subclass of class/group. The existing statements on the two items make that clear without reliance on a distinction between "group" and "class". Swpb (talk) 14:46, 22 May 2023 (UTC)

@Swpb: a concrete object necessarily doesn't have a physical referent (see en:abstract and concrete). E.g. also McLaren Technology Group (Q173146) (corporate group) is a group and a concrete object. group of physical objects (Q61961344) and other types of groups should be set as subclasses of general group item that no longer exists after your merge.

I don't see any good reason to use a single class (this item) for two contradicting purposes. This is just messy and it leads to many dissonances, e.g. classes like group of lakes (Q5926864) could set as an instance and a subclass of the same class then, and also it's erroneously indicated that Great Lakes (Q7347) is a class.

As said, statements in Q16887380 were messy, but uses of this item do imply that it's intended to be a class of concrete objects. Currently 21,455 items are set as direct instances of Q16887380. These instances are mostly concrete objects like 14th Street – Union Square (Q2631031) and Five Dynasties (Q20716233), not classes as suggested by redirect target. Additionally there are currently 220 items set as direct subclasses of Q16887380, e.g. island group (Q1402592) which is a more specific class of concrete groups.

So I think it's better to restore the group item soon enough to avoid further big scale mess once redirect-solving bots have processed all these links. 2001:7D0:81FD:BC80:8507:95E7:7B4B:8CE1 17:07, 22 May 2023 (UTC)

Very well, you can revert so the redirect-solving bots don't do anything while we discuss - but I still don't think there's as clear of a distinction here as you suggest. As the Wikipedia article says, "There is no general consensus as to what the characteristic marks of concreteness and abstractness are". As I see it, Great Lakes (Q7347) is a class, which is the same thing as a group, with five lakes as members. If there is a firm, consistent difference in meaning between "group" and "class", then the statements and labels on the two items (and also on concrete object (Q4406616)) are in dire need of cleanup to explain what that difference is. Swpb (talk) 18:00, 22 May 2023 (UTC)

These items are protected and so unfortunately I can't revert myself. I agree that these items are in dire need of cleanup.

I wrote about abstract and concrete objects as the distinction between the two broadly and regardless of exact definitions corresponds to Wikidata's basic distinction between classes and instances (see Help:Basic membership properties). In this context, and I'd say also in any other common sense of word "class", Great Lakes is not a class. It'd be incorrect to set Great Lakes as a subclass of some parent class, and it'd be incorrect to consider that Great Lakes in turn has instances instead of parts. 2001:7D0:81FD:BC80:B563:428:D200:1082 19:04, 22 May 2023 (UTC)

I've reverted the merge for now. But for the record, this supposed group/class distinction does not correspond to Wikidata's instance/class distinction. I'm more than familiar with Help:Basic membership properties, and this concrete/abstract notion isn't in there. Great Lakes (Q7347) meets the definition given on class (Q16889133): "a collection of items sharing common characteristics", so I think the burden is on you to explain how it isn't a class. Swpb (talk) 19:07, 22 May 2023 (UTC)

I think I see a distinction in how class (Q16889133) and group (Q16887380) are defined and used, but it has nothing to do with whether the members are concrete or abstract: instead, it has to do with whether membership is criterion-based (class) or enumerated (group). lake (Q23397) is a class, because there are criteria to decide if something is a lake or not. The Great Lakes are a group, because membership is determined by checking a list with five names on it. That, I think, captures the difference in how class (Q16889133) and group (Q16887380) are used, and should be emphasized, rather than applying the nebulous concrete/abstract distinction that, frankly, is not expressed in the existing statements, labels, or definitions (at least in English). Swpb (talk) 19:23, 22 May 2023 (UTC)

Thanks for the revert. Of course group/class distinction isn't the instance/class distinction. A group is a kind of instance. This help page does define class as (kind of) abstract object. To me it seems quite straightforward to consider instances as concrete objects accordingly. But yes, it is difficult to explain classes/instances so that to general audiance it wasn't overly complicated nor overly simplified.

Generally, Wikidata item descriptions aren't reliable, they can be messed up easily. Current description in Q16889133 is at best so general that it's useless when it comes to class/group distinction. This broad description also applies to, say, ship (Q11446) (a particular class) as much as it applies to "group", but this doesn't mean that "ship" and "class" are the same (nor that Great Lakes in turn is a ship).

We might look for definitions in some more authoritative databases/ontology related source. But I think it's more simple and more practical to draw the class/group distinction from how basic membership properties are used in Wikidata. As mentioned, group has parts, unlike classes it doesn't have subclasses or instances. See also Talk:Q16887380 on attempts to define group more clearly and another discussion referenced over there about class/group distinction.

I think your criterion-based classes and enumeration-based groups also do capture the difference, kind of. I'd avoid calling subclasses as "members", though, as it resembles parts. As for meeting the criteria, yes, a class represents something its subclass also is. Whereas group member is not what the group is. Weak part of this criterion-enumeration distinction is that all subclasses of a class in some cases may may be enumerated as well (e.g. some legal status that has fixed number of subtypes defined in a law text), and also inclusion to a group in some cases may be criterion based (say, there's some group of rich countries that automatically includes a member if it meets certain GDP threshold). 2001:7D0:81FD:BC80:B563:428:D200:1082 20:52, 22 May 2023 (UTC)

Group is a not a class. Members of a group do not need to have shared characteristics. --Dan Polansky (talk) 07:45, 24 June 2023 (UTC)

A group is not necessarily one of concrete objects; it can be one of abstract objects. That does not matter. Group, like a mathematical set, can be identified extensionally, via a list of its member entities. That is not true of a class. Thus, a group of humans does not necessarily form a class. A group of abstract objects such as qualities (say, blueness, redness, and yellowness) is not a class. "X is a member of group Y" is very different from "X is an instance of a class Y", as well. --Dan Polansky (talk) 10:40, 24 June 2023 (UTC)

Well, both words "class" and "group" are used in various senses, and here for a start we need to figure out which particular sense corresponds to item subject. Groups like a group of humans or a group of qualities you listed are not mathematical groups (Q83478).

As for concrete objects, these are not necessarily only physical objects, if that's what you suggest. For instance one can feel a concrete mix of feelings even if it's a mix of feelings that individually are abstract. 2001:7D0:81DB:1480:DCB1:F13C:6E9C:6C41 07:50, 25 June 2023 (UTC)

I am using the words in some of the most usual sense defined in dictionaries, by which it is part of a definition of a class that its items share some common characteristics by which they are selected into the class, and that is not true of a group.

As for concrete vs. abstract, I am using the terms in the sense of Wikidata "concrete object" and "abstract object", which I think match Stanford Encyclopedia of Philosophy, by which feelings are not abstract, from what I understand. In any case, my whole point was that whatever usual contrast of abstract vs. concrete one takes, that contrast is orthogonal to the contrast of class and group. We can have a class of concrete objects and a different class of abstract objects; we can have a group of concrete objects and a different group of abstract objects. --Dan Polansky (talk) 09:55, 26 June 2023 (UTC)

It's a bit unclear to me in response to what exactly you wrote your previous comment. As for classes being different from groups, yes, this is what I also tried to convey in my original post. My comment about words and senses was to point that in part you wrote about groups in two distinct senses in a jumble, and that's not helpful really.

As for "concrete object" item, I find it is misleading in its current form. I left a comment about it in its talk page earlier. 2001:7D0:81DB:1480:6D54:95F0:8179:1D72 09:34, 27 June 2023 (UTC)

Well said. It's the extensional aspect of groups that makes them different from classes, not a concrete vs. abstract distinction. Groups are defined by a list, classes by a rule. Swpb (talk) 15:52, 27 June 2023 (UTC)

The domain of ontology

This entity needs to remain in the domain of ontology as long as "concept" is tracked as a synonym/alias, which it is. That is my understanding. If the context is removed, the removal should be accompanied by a rationale, whether on the talk page or via edit summary. --Dan Polansky (talk) 07:51, 24 June 2023 (UTC)