Wikidata:Property proposal/algebraic properties

identity elementEdit

Originally proposed at Wikidata:Property proposal/Natural science

Descriptionvalue of the identity element of the mathematical operation
Representsidentity element
Data typeItem
Domainbinary operation (Q164307)
Allowed valuesmathematical object (Q246672)
Example 1addition (Q32043)zero (Q204)
Example 2multiplication (Q40276)1 (Q199)
Example 3function composition (Q244761)identity (Q254474)
Example 4matrix addition (Q2264115)zero matrix (Q338028)
Example 5matrix multiplication (Q1049914)identity matrix (Q193794)

More examples: [1].

mathematical inverseEdit

Originally proposed at Wikidata:Property proposal/Natural science

Other examplesEdit

has operatorEdit

Originally proposed at Wikidata:Property proposal/Natural science


Algebriac groups are an important class of mathematical object. In Wikidata, there are 184 instances [2] and 585 subclasses [3] of algebraic groups, but they are lacking the most basic information to describe them. A group consists of a mathematical set (Q36161) and an invertible binary operation (Q164307), which has a unique identity element (Q185813). In order to model this information, I propose creating three new properties: identity element, mathematical inverse, and has operator. (These properties are applicable beyond just groups, however. Multiple examples are listed above.)

Existing properties are inadequate or cumbersome for modeling these relationships. We could model "identity element" and "has operator" with existing properties by using has part (P527), but it results in set of real numbers (Q26851380) has part (P527) zero (Q204) / subject has role (P2868) identity element (Q185813) / relative to (P2210) addition (Q32043) and set of real numbers (Q26851380) has part (P527) addition (Q32043) / subject has role (P2868) group operation (Q99839939) but that is super convoluted and querying it would be difficult. Similarly, we can model "mathematical inverse" as −1 (Q310395) opposite of 1 (Q199) / relative to (P2210) addition (Q32043) / criterion used (P1013) mathematical inverse but, again, this is awkward and also prevents us from enforcing expected relationships, such as the symmetry of inverses.

I considered three ways of modeling identity element:

  1. set of real numbers identity element zero / with respect to addition
  2. set of real numbers has operation addition / identity element zero
  3. set of real numbers has operation addition addition identity element zero

Option 1 was dismissed because an "identity" is an identity of an of the operator rather than the set, so the modeling should reflec that. Option 2 is an improvement over option 1---and we might want to use "identity element" as a qualifier sometimes (please discuss)---but I think option 3 is best choice because it is simple and will prevent duplication if the same operator is used on multiple structures. (Option 3 might be problematic, however, if some algebraic structure, let's call it  , uses an operator that has an identity element  , but  . I don't know if this is possible or not.)

The Erinaceous One 🦔 10:53, 2 October 2020 (UTC)


<ping project should not be used in an indented reply> Opensofias
Arthur Rubin
Nomen ad hoc
The Anome
Daniel Mietchen
  Notified participants of WikiProject Mathematics

  Support for all of these; however I have a question about the "mathematical inverse" proposal - two of your examples have the qualifier and two don't - does that suggest these are two distinct properties, or is there a better way to describe this? ArthurPSmith (talk) 20:51, 2 October 2020 (UTC)
@ArthurPSmith: No, it should only be one property. I've added a qualifier for the sine/arccosine example and qualfier would work on the Laplace transform example, but I'm not sure what the right qualifier value is. We could use Laplace transform (Q199691) mathematical inverse inverse Laplace transform (Q2162701) / relative to (P2210) function composition (Q244761), but I'm not sure if it's accuracte to talk about the function composition of integral transforms. (I.e. is an integral transformation a function on functions?) — The Erinaceous One 🦔 22:14, 2 October 2020 (UTC)
I've thought about it more and Laplace transform (Q199691) mathematical inverse inverse Laplace transform (Q2162701) / relative to (P2210) function composition (Q244761) is correct, so now all the "mathematical inverse" examples have qualifiers. — The Erinaceous One 🦔 21:45, 3 October 2020 (UTC)

@Jura1, Ederporto: would one of you be able to create these properties? — The Erinaceous One 🦔 09:06, 11 November 2020 (UTC)

@The-erinaceous-one, ArthurPSmith, Tinker Bell:   Done identity element (P8864), mathematical inverse (P8865), has operator (P8866) Pamputt (talk) 17:07, 26 November 2020 (UTC)