Property proposal:	Generic	Authority control	Person	Organization
	Creative work	Place	Sports	Sister projects
	Transportation	Natural science	Computing	Lexeme

Physics/astronomy

Please review Wikidata:WikiProject Physics before proposing. Ping members of project using {{Ping project|Physics}}
See also Wikidata:Property proposal/Pending for approved items awaiting the deployment of currently unavailable datatypes.
Please look at Wikidata:List of properties/science/natural science before proposing a property.

Biology

Please visit Wikidata:WikiProject Taxonomy for more information. To notify participants use {{Ping project|Taxonomy}}

Please visit Wikidata:WikiProject Biology for more information. To notify participants use {{Ping project|Biology}}

Embryo Project Encyclopedia ID

Under discussion

Description	ID of an entry in Embryo Project Encyclopedia
Data type	External identifier
Example 1	Lewis Terman (Q919108) => lewis-madison-terman-1877-1956
Example 2	Buck v. Bell (Q2891943) => buck-v-bell-1927
Example 3	Labor and delivery outcomes among young adolescents (Q40983883) => labor-and-delivery-outcomes-among-young-adolescents-2015-ana-j-torvie-lisa-s-callegari-melissa
External links	Use in sister projects: [ar] • [de] • [en] • [es] • [fr] • [he] • [it] • [ja] • [ko] • [nl] • [pl] • [pt] • [ru] • [sv] • [vi] • [zh] • [commons] • [species] • [wd] • [en.wikt] • [fr.wikt].
Formatter URL	https://embryo.asu.edu/pages/$1

Partial Mix'n'Match catalog

Motivation

The Embryo Project Encyclopedia is a digital publication for topics related to the sciences of developmental biology and reproductive biology, and for the historical, legal, ethical, and social contexts of those sciences.--GZWDer (talk) 14:06, 26 February 2025 (UTC)[reply]

Discussion

Support --Trade (talk) 20:20, 6 March 2025 (UTC)[reply]

‎breed belongs to taxon

Under discussion

Description	taxon to which members of this breed (or these breeds) belong
Aliases	breed taxon \| breeds belong to taxon \| taxon of this breed \| taxon of these breeds \| is a breed of taxon
Data type	Item
Domain	breed (Q38829)
Allowed values	instances of taxon (Q16521)
Example 1	Churra Tensina (Q2881542)breed belongs to taxonMongolian Bactrian (Q108198705)
Example 2	Zhongdian-Yak (Q197824)breed belongs to taxonBos mutus (Q26547)
Example 3	pigeon breed (Q15623573)breed belongs to taxondomesticated pigeon (Q204179)
See also	see Motivation

Constraints

Motivation

To link breeds, or classes of breeds, of a particular taxon to that taxon. There is currently no appropriate property for this purpose:

The qualifier of (DEPRECATED) (P642) (130 current uses) is deprecated.
subclass of (P279) (44 current uses) generally results in a value-requires-statement constraint violation, e.g. on Q133892473), as taxa use parent taxon (P171) rather than subclass of (P279).
parent taxon (P171) (3 current uses) is subject-constrained to use on taxa, which breeds are technically not.
facet of (P1269), found in taxon (P703), and natural product of taxon (P1582) have also been used for this purpose, but are also inappropriate per their descriptions and constraints.

Swpb (talk) 14:51, 13 May 2025 (UTC)[reply]

Discussion

WikiProject Taxonomy has more than 50 participants and couldn't be pinged. Please post on the WikiProject's talk page instead.

Notified participants of WikiProject Biology

Support Useful and necessary. Christian Ferrer (talk) 16:48, 13 May 2025 (UTC)[reply]
Comment That constraint on the subclass of relation is kind of annoying with taxa. ArthurPSmith (talk) 18:26, 13 May 2025 (UTC)[reply]
- Agreed, but value-requires-statement constraint (Q21510864) does not seem to support an OR condition: in sandbox, adding property (P2306)=parent taxon (P171) just breaks the constraint. And I'm not looking to challenge the consensus that taxa should use parent taxon (P171) instead of subclass of (P279). (Arguably, the constraint type should allow any property that is a sub-property of the listed property, which parent taxon (P171) is to subclass of (P279), but again, changing that is not exactly the path of least resistance.) Swpb (talk) 18:58, 13 May 2025 (UTC)[reply]
Comment I wonder if the value-requires-statement constraint could be changed so it doesn't require the taxon to be any subclass of. I think it's already unambiguous if an item that is an instance of breed (or subclass thereof like dog breed (Q39367)) is a subclass of sth, it's a breed that belongs to the taxon in subclass. --Prototyperspective (talk) 13:10, 15 May 2025 (UTC)[reply]
- Agreed that subclass of (P279) would be unambiguous, but as I said above, it doesn't seem there's a way to modify the constraint to allow that usage without breaking the whole constraint. An alternative would be to re-scope parent taxon (P171) to "closest parent taxon of the taxon or breed in question" and likewise expand its subject-type constraint, but Christian Ferrer (above) was not in favor of that idea. If you think that's the way to go though, we can look for consensus on it. ArthurPSmith, what do you think of that? Swpb (talk) 13:48, 15 May 2025 (UTC)[reply]
  No strong opinion from me except that it's messy - I don't want to upset the taxonomy consensus here! ArthurPSmith (talk) 14:41, 15 May 2025 (UTC)[reply]
  - Personally I think it's hard enough to make the taxonomic content work well as regard to our external sources, and to the different Taxonomic codes (zoological, botanical,..), and as regard to the small number of experienced users who are currently dealing with taxonomic content in Wikidata, to not extend the scope of taxonomic properties. Question? why, if "parent taxon" would fit it, not to put the same kind of constraint on this new properties, I have read all the comment above but I can't grasp the technical problem. Christian Ferrer (talk) 15:07, 15 May 2025 (UTC)[reply]
    - The technical problem is this: subclass of (P279) has this constraint, which says that the value of P279 must always have its own P279 statement, so that everything is connected to the subclass tree. If we use P279 with a taxon as value, it fails this constraint, because most taxon items don't have a P279 statement (because they use parent taxon (P171) instead). The constraint cannot be modified to accept a second property (see here for why). If breed items use P171 or the proposed property, they don't trigger a violation, because those properties don't have the same constraint that P279 has. Swpb (talk) 17:52, 15 May 2025 (UTC)[reply]
      - Sorry I can't understand, thanks you for the links and explanation, but it remains confusing to me, it's probably too technical. I don't see why this would not work:
subject type constraint (Q21503250)
- class (P2308) breed (Q38829)
- relation (P2309) instance of (Q21503252)
property scope constraint (Q53869507)
- property scope (P5314) as main value (Q54828448)
value-type constraint (Q21510865)
single-value constraint (Q19474404)
- constraint status (P2316) suggestion constraint (Q62026391)

Christian Ferrer (talk) 20:58, 15 May 2025 (UTC)[reply]

Those are all perfectly sensible constraints for the property being proposed here. What we're talking about is why we can't use P279 instead of this new property, and the value-requires-statement constraint on P279 is the reason why. Swpb (talk) 23:34, 15 May 2025 (UTC)[reply]

Oh yes, got it, now I understand, thanks you. But anyway this seems to be a good thing to me because I don't think P279 ontologically adapted for that. Christian Ferrer (talk) 03:48, 16 May 2025 (UTC)[reply]

Comment I think it may be an step in the direction of clarifying what taxa are, or are not, on Wikidata. In that sense, I tend to Support it. But I also align with ArthurPSmith: No strong opinion from me except that it's messy! TiagoLubiana (talk) 15:00, 19 May 2025 (UTC)[reply]

Oh, the example "pigeon breed (Q15623573) belongs to taxon domesticated pigeon (Q204179)" is for me a bit weird.

Like, "pigeon breed" is one ontological layer above any actual breed, say Dutch Curled Cropper (Q26736184), which makes usage also a bit messy.

Not sure how to fix it though, but maybe make it clear that the property can be used for both the classes and the metaclasses. TiagoLubiana (talk) 15:05, 19 May 2025 (UTC)[reply]

I tried to make that clear with the parenthetical in the description, and the aliases that refer to "breeds" plural. The label could be "breed(s) belong to taxon", although most uses by far will be on individual breeds. The same value-requires-statement constraint that subclass of (P279) has appears on is metaclass for (P8225) too, otherwise that would be the correct property for classes of breeds. Swpb (talk) 17:36, 19 May 2025 (UTC)[reply]

Biochemistry/molecular biology

Please visit Wikidata:WikiProject Molecular biology for more information. To notify participants use {{Ping project|Molecular biology}}

Chemistry

Please visit Wikidata:WikiProject Chemistry for more information. To notify participants use {{Ping project|Chemistry}}

‎molecular formula

Under discussion

Description	Description of chemical compound giving element symbols and counts
Represents	molecular formula (Q188009)
Data type	Item
Domain	type of chemical entity (Q113145171) group of stereoisomers (Q59199015)
Allowed values	molecular formula (Q188009)
Example 1	2-hydroxy-5-octanoylbenzoic acid (Q209407)→C₁₅H₂₀O₄ (Q129998552)
Example 2	abscisic acid (Q332211)→C₁₅H₂₀O₄ (Q129998552)
Example 3	Santonic acid (Q7420590)→C₁₅H₂₀O₄ (Q129998552)
Example 4	silver bicarbonate (Q27260276)→CHAgO₃ (Q130044611)
Expected completeness	always incomplete (Q21873886)
See also	chemical formula (P274)
Wikidata project	WikiProject Chemistry (Q8487234)

Notified participants of WikiProject Chemistry

Motivation

This proposal addresses the need for improved data structure and maintenance within Wikidata’s chemical compound data. Currently, the Wikidata:WikiProject Chemistry manages approximately 1 million chemical items, with many of them linked to chemical formula (P274) and mass (P2067). The main issues are:

Redundancy in Data: With about 300,000 unique chemical formula strings in use, redundancy is a significant problem. Some strings are associated with over 1,000 items, which complicates data management (see https://w.wiki/B2ax).

Efficiency and Maintenance: Transitioning from string-based formulas to item-based ones will simplify maintenance, reduce redundancy, and optimize query performance, especially for SPARQL queries involving formulas or masses.

Data Optimization: Moving mass (P2067) statements to the newly created formula items will reduce the number of triples and make data management more efficient. Additionally, this change will facilitate the use of different units for masses and allow for better structured data.

Improved Modeling: Switching to item-based formulas could eliminate the need for overly complex has part(s) (P527) statements on chemicals, allowing cleaner, more precise data models (e.g., identifying all chemical formulas containing more than five oxygen atoms).

This change is expected to bring numerous benefits, including reduced redundancy, improved query efficiency, and better data maintenance. The potential downside of increased label editing can be managed, and the overall gain for Wikidata’s chemical data justifies this proposal. If approved, I am prepared to create the necessary items and migrate existing data.

Any further input to refine this proposal is more than welcome!

P.S.: I have no strong opinions if current chemical formula (P274) should be deleted or used on the new items as "Chemical Formula String" – The preceding unsigned comment was added by AdrianoRutz (talk • contribs) at 15:00, August 28, 2024‎ (UTC).

discussion

Support sounds great! Egon Willighagen (talk) 15:25, 28 August 2024 (UTC)[reply]
Comment Last night on the boat between Finland and Sweden I thought of another aspect where this would help model the chemistry in Wikidata better. If chemical formula are items (and thanks to GZWDer for showing various Wikipedias decided it was useful too), then they can also subclass each other. We can have an isotope-agnostic chemical formula ( the common case) and subclasses for chemical formula with isotopes.As such it does much more than being something technical (e.g. just about scalability) but actually improve how we talk about the chemistry. Egon Willighagen (talk) 07:07, 29 August 2024 (UTC)[reply]
Some comments:

I will oppose "Additionally, this change will facilitate the use of different units for masses and allow for better structured data." - For consistency and machine-readability we should stick to one unit. I instead propose Wikidata:Property proposal/formula weight.
Many wikis has pages like C15H20O4 (Q1250089). Some wikis treat it as disambiguation pages; some as set indices; we need to discuss how to handle such existing items. GZWDer (talk) 21:10, 28 August 2024 (UTC)[reply]

I looked at the English Wikipedia sitelink-ed page, and that actually looks exactly like a page about a chemical formula. To be honest, this actually sounds like in argument in favor of this proposal and that C15H20O4 (Q1250089) should be of type chemical formula (Q83147). The same for the French WP page, and neither say they are disambiguation pages, but are far more like a category of things with the same property. Just like this proposal, not? Egon Willighagen (talk) 06:58, 29 August 2024 (UTC)[reply]

I was only partially able to follow your mind here. In your proposal, you mention this property if created, thus you would support it? I believe the discussion about mass (P2067) (and units) or other properties is an interesting one this proposal would allow to better discuss/implement, and what I mentioned about these or what is currently on the example item are just ideas, if this new property allows for these things to also improve, even better! AdrianoRutz (talk) 08:51, 30 August 2024 (UTC)[reply]

Weak oppose I cannot question arguments raised here about efficiency, but I don't see this as a proper way forward. This proposal completely fails to take into account the fact that for a given chemical entity there may be many – equally correct – chemical formulae (simple example in Q27260276#P274). Moving chemical formulae to another item will not help at all with the most important purpose for which WD exists – using this data. I would see the new property as being created only to assist with specific activities – but not to replace existing properties – and with appropriate disclaimers in the name and constraints that it is a strictly technical property only. Wostr (talk) 22:21, 28 August 2024 (UTC)[reply]
I think this proposal has no problems with alternative formula notations, e.g. like CHAgO₃ (Q130044611). Or? Egon Willighagen (talk) 06:51, 29 August 2024 (UTC)[reply]
CHAgO₃ and AgHCO₃ are not the same chemical formula. Just as e.g. XeF4O and XeOF4 which would require two different items for the same compound. In fact, for some compounds several new items would need to be created. For some chemical species we would have formulae that have different number of atoms of elements: C₃₀H₄₀F₂N₈O₉, C₁₅H₁₇FN₄O₃·1,5H₂O and C₃₀H₃₄F₂N₈O₆·3H₂O are correct formulae for the same compound, but I don't see a way for this to be reflected correctly by the current proposal. Everything looks fine if you consider only simple organic compounds and their formulae in Hill notation, but it's not that simple especially if we consider some inorganic compounds which are not molecules. Wostr (talk) 12:34, 29 August 2024 (UTC)[reply]
Thank you for this important point! I removed the single value constraint, thus allowing for what you mention. AdrianoRutz (talk) 08:47, 30 August 2024 (UTC)[reply]

Good point about non-molecular substances. I think the chemical concept we are trying to capture is that of isomerism: chemical entities are isomers when they have the same molecular formula (Q188009) or (non-structural) formula unit (Q1437643), enabling one molecule/ion/unit of the first chemical entity to be rearranged into one molecule/ion/unit of the second chemical entity by moving atoms/bonds around.
For example, the ionic compounds with structural formulas [CrCl(H₂O)₅]Cl₂•H₂O and [Cr(H₂O)₆]Cl₃ are (hydration) isomers, which we can recognise by assigning them the same formula H₁₂Cl₃CrO₆. This shows that all species in the crystal lattice of a compound should be combined together into a single entity when determining the formula. In the example you give above, the correct formula would be C₃₀H₄₀F₂N₈O₉, derived from combining together 2C₁₅H₁₇FN₄O₃•3H₂O, the smallest formula unit with integer multiples of all species.

Likewise, the molecular substance CO(NH₂)₂ and ionic compound NH₄OCN are considered isomers, which we can recognise by assigning them the same formula CH₄N₂O. This is the molecular formula of urea and the formula unit of ammonium cyanate, showing how molecular and non-molecular substances can be isomeric.

For ions, fulminate(1−) (Q27110286) (with structural formula CNO^-) and cyanate anion (Q55503523) (with structural formula OCN^-) are isomers, which we can recognise by assigning them the same formula CNO^-.

Clathrates are similar to coordination compounds. E.g. methane clathrate (Q389036) has structural formula 4CH₄•23H₂O, yielding the formula C₄H₆₂O₂₃. Likewise, the endohedral fullerene CH₄@C₆₀ should have formula C₆₁H₄.

Compounds should not usually map to multiple formulas: if C links to two different formulas, one the same as A (from reference 1) and one the same as B (from reference 2), this implies C is isomeric with A, and C is isomeric with B, but A is not isomeric with B. This only makes sense if 1 and 2 disagree as to what the correct formula of C ought to be.

When references disagree, we may need to support multiple formulas. Historically, w:en:copper monosulfide was thought to have structure [Cu²⁺][S^2-], corresponding to the formula CuS. It has now been assigned the structure [Cu⁺]₃[S^2-][S₂^-], which would correspond to Cu₃S₃. However, PubChem still has the old formula. We might want to update Wikidata to the new formula while also keeping the PubChem-referenced formula (with a note that it's not the correct formula).

Non-stoichiometric compounds, alloys, and mixtures of indeterminate composition are more complicated to support. E.g. pyrrhotite (Q421944) has formula Fe_1-xS (x = 0 to 0.125). Rather than trying to support formula units with atom counts that are algebraic expressions (e.g. 1 - x), I think it would be easier if we could list the formulas of the endpoints: Fe₇S₈ and FeS. Similarly, superconducting yttrium barium copper oxide (Q414015) has formula YBa₂Cu₃O_7−x (x = 0 to 0.65), with endpoint formulas YBa₂Cu₃O_6.35 (i.e. Y₂₀Ba₄₀Cu₆₀O₁₂₇) and YBa₂Cu₃O₇. I think it's hard to come up with a perfect solution though. InChI (P234) has similar issues for non-stoichiometric compounds: https://doi.org/10.1186/s13321-015-0068-4#Sec45.

Preimage (talk) 17:47, 31 August 2024 (UTC)[reply]
Support I also see more benefits than downsides. Support. Wostr I am not sure to understand how this would be a problem even for entities which could be described using different MF sequences of atoms like Q27260276#P274. Indeed the has part(s) (P527) and quantity (P1114) of the MF entity, see C₁₅H₂₀O₄ (Q129998552) would allow to efficiently retrieve such compounds represented in different MF notation systems. What would exactly be the inconvenient in this particular case? GrndStt (talk) 06:22, 29 August 2024 (UTC)[reply]
Support, conditional on change of representation to molecular formula (Q188009). As noted in w:en:chemical formula#Types, chemical formula (Q83147) has four separate meanings: empirical formula (e.g. formaldehyde and glucose both have empirical formula CH₂O), molecular formula (e.g. urea and ammonium cyanate both have molecular formula CH₄N₂O in Hill notation, indicating they are isomers), structural formula (a graphical representation of the structure, not so relevant here), and condensed (or semi-structural) formula (e.g. urea has condensed formula CO(NH₂)₂ whereas ammonium cyanate has condensed formula [NH₄][OCN]). Molecular formulas "indicate the simple numbers of each type of atom in a molecule, with no information on structure", which is what we need for mass calculations. They also avoid the issue raised by Wostr regarding non-uniqueness of chemical formulas (e.g. NH₄NO₃ and H₄N₂O₃ are both valid formulas for ammonium nitrate), as each chemical should have a single canonical molecular formula in Hill notation (with the exception of rare cases where there is disagreement regarding structure, e.g. w:en:copper monosulfide). One last potential issue: molecular formulas are often defined as not including isotopes, e.g. PubChem lists both deuterated chloroform and chloroform as having molecular formula CHCl₃. Egon Willighagen's suggestion to have a subclass of [molecular] formulas with isotopic information would resolve this issue though, I think. Preimage (talk) 12:22, 29 August 2024 (UTC)[reply]
Just revised the naming to change to molecular formula (Q188009), as suggested. 👍🏼 AdrianoRutz (talk) 07:16, 24 September 2024 (UTC)[reply]
Oppose A chemical formula is an abstract entity and not one that has a mass.

It's worth noting that unicode can't capture all chemical formula and Mathematical expression could express more. ChristianKl ❪✉❫ 16:29, 25 September 2024 (UTC)[reply]

You're wrong about that. Each chemical formula has a defined number of atoms of a defined number of elements. Although each element has multiple isotopes, for every element with stable isotopes there is a standard mass associated with it which is the atomic weight which will be found with a typical sample. So the molecular weight of a particular chemical formula very much can be expressed. David Newton (talk) 09:58, 27 September 2024 (UTC)[reply]

Currently, in Wikidata a chemical formula is a notation. Notations don't have inherent mass. The NCI description of what a chemical formula happens to be is "representation of a substance using symbols for its constituent elements". It's not the object that it's describing. While the object that a formula is describing can have mass the formula itself doesn't. It's a Document in NCI's ontology. In PROCO it's a quality and also not something that has mass. material entity (Q53617407) have mass and molecular formula (Q188009) isn't. ChristianKl ❪✉❫ 12:47, 9 October 2024 (UTC)[reply]

The proposed items for formulas could make sense if we interpret the items as representing classes of those chemical entities that consist of the specified number of each element, regardless of bonding. Those underlying chemical entities do have a particular mass (up to some tiny difference due to mass-energy equivalence). 73.223.72.200 05:23, 16 December 2024 (UTC)[reply]

Indeed. The form of "mass" we are trying to capture is w:en:Mass (mass spectrometry)#Average mass, within which formulas do have inherent mass and isomers have exactly identical masses. Preimage (talk) 14:37, 16 December 2024 (UTC)[reply]

Comment - This proposal strikes me as a hack to work around Wikibase's lack of support for computing properties. It seems more straightforward to update the software to compute the mass. As proposed, in the fairly common case that there's currently only one notable compound with a given formula, would we be creating an additional item just to hold properties like mass? That seems counterproductive wrt efficiency and redundancy. 73.223.72.200 05:23, 16 December 2024 (UTC)[reply]
Understood. But we have been waiting over eight years for Wikibase to support computed properties.

In the absence of computed properties, we should use a formula representation that makes downstream processing easier. E.g. suppose I want to set up property constraints to identify chemicals with molecular masses inconsistent with their molecular formulas. At present, chemical formula (P274) uses a string representation, which makes such processing more difficult than it ought to be. Switching to a molecular formula representation that links to elements using the has part(s) (P527) and quantity (P1114) properties would solve this problem.

Another example: organic compounds with F mol% (excluding H) >= 30% are considered to be per- and polyfluoroalkyl substances (Q648037) under the EPA's PFASSTRUCTv5 definition. At present, to test this for a given organic compound, we need to (1) split the chemical formula (P274) string up into element-specific chunks, (2) parse each chunk, (3) combine chunks matching the same element, (4) compute the number of atoms excluding H, (5) compute the number of F atoms, and (6) compute the F mol% (excluding H). The proposal we are discussing here would allow us to skip steps 1–3. Preimage (talk) 13:00, 17 December 2024 (UTC)[reply]
Support --Trade (talk) 20:21, 6 March 2025 (UTC)[reply]
Oppose mass (P2067) and has part(s) (P527) are properties of chemical compound, not its formula. Midleading (talk) 02:41, 2 April 2025 (UTC)[reply]
So, "CH₄N₂O" does not has part(s) (P527) "C", "H", "N", "O"? And you cannot determine the mass of such entity? A chemical compound also has no single mass (P2067), but the chemistry community on Wikidata still has the sensible approach to try to model things in a good consistent yet approximative way. This proposal won't solve all problems as mentioned above but will already allow to do slightly better. AdrianoRutz (talk) 05:55, 2 April 2025 (UTC)[reply]
CH₄N₂O should exist as a string value not as an item, this is the current modeling approach. Your proposal seems too big in scope that a RfC may be more appropriate. Midleading (talk) 16:57, 2 April 2025 (UTC)[reply]
Oppose It seems better to ~~create a property for isomer (Q127950)~~ and leave chemical formula (P274) as is. – The preceding unsigned comment was added by 慈居 (talk • contribs) at 17:04, April 24, 2025 (UTC).
- Modeling things this way would result in thousands of many-to-many relationships, making the situation significantly worse. AdrianoRutz (talk) 19:55, 4 May 2025 (UTC)[reply]
  - The current chemical formula (P274) will be enough. Items for chemical formulas carry no additional information other than the fact that the molecular weight is calculated based on them. 慈居 (talk) 21:32, 4 May 2025 (UTC)[reply]

Medicine

Please visit Wikidata:WikiProject Medicine for more information. To notify participants use {{Ping project|Medicine}}

Mineralogy

Please visit Wikidata:WikiProject Mineralogy for more information. To notify participants use {{Ping project|Mineralogy}}

Computer science

Please visit Wikidata:WikiProject Informatics for more information. To notify participants use {{Ping project|Informatics}}

Geology

Please visit Wikidata:WikiProject Geology for more information.

Geography

‎SOIUSA code

Under discussion

Description	Identifier of mountains, summits, mountain groups, etc. according to the International Standardized Mountain Subdivision of the Alps (SOIUSA)
Represents	SOIUSA code (Q1628678)
Data type	External identifier
Template parameter	codice in it:template:Montagna
Domain	mountain, summits, mountain groups: summit (Q207326), mountain (Q8502), ridge (Q740445), ridge section (Q131521567), arête (Q1334383), back of a mountain (Q820144), mountain shoulder (Q15787792), ranks of the SOIUSA taxonomy: alpine main part (Q131311255), alpine major sector (Q3775635), alpine section (Q3958626), sector of alpine section (Q3958438), alpine subsection (Q3965305), sector of alpine subsection (Q3958440), alpine supergroup (Q3977906), sector of alpine supergroup (Q3958437), alpine group (Q3777462), sector of alpine group (Q131604769), alpine subgroup (Q514999), sector of alpine subgroup (Q3958436)
Allowed values	[I\|II](/[A-C](-[1-36](/[A-B])?(\.[I\|II\|III\|IV\|V\|VI\|VII\|VIII](/[A-B])?(-[A-F](/[a-z])?(\.[1-22](/[a-z])?(\.[a-z](/[a-z])?)?)?)?)?)?)?
Example 1	Punta Sommeiller (Q2279001) → I/A-4.III-B.6.b
Example 2	Hochgrat (Q459121) → II/B-22.II-B.5.b
Example 3	Winterstaude (Q2585140) → II/B-22.I-B.6.b
Example 4	Übelhorn (Q130718862) → II/B-22.II-D.12.a/b
Source	https://it.wikipedia.org/wiki/Suddivisione_Orografica_Internazionale_Unificata_del_Sistema_Alpino
Planned use	Indification where different geographic features of the Alps (mountains, summits, groups on different levels, sections, sectors, parts) belong from an orographic perspective
Number of IDs in source	3498 (2 main parts + 5 major sectors + 36 sections + 132 subsections + 333 supergroups + 870 groups + 1625 subgroups + 31 sectors of sections + 30 sectors of subsections + 18 sectors of supergroups + 7 sectors of groups + 409 sectors of subgroups)
Expected completeness	eventually complete (Q21873974)
Single-value constraint	yes

Motivation

The IDs are already used to a certain extend by different Wikimedia projects in articles on mountain ranges and mountains of the Alps. Due to their hierarchical structure, they are useful to locate a summit or mountain in its closer or wider context. They can also support the identification of duplicates as well as to distinguish different summits/mountains that have the same name since the likelihood of two mountains or summits with the same name being located in the exact same alpine subgroup is low and therefore it is unlikely that two mountain features with the same name have the same SOIUSA code.

-- Harald Hetzner – The preceding undated comment was added at 20:00, 29 December 2024.

Discussion

Support, if restricted to the ranks of the SOIUSA taxonomy (as listed above), Oppose, if also intended for features like mountain (Q8502) (it is not a property of an individual mountain, but of the hierarchical embedding). The examples above all are mountains and do not match the use as I would restrict it. (see also User_talk:Herzi_Pinki#Property_Proposal_zu_SOIUSA-Code (German)). Don't see how this property supports the identification of duplicates as well as helps to distinguish different summits/mountains that have the same name (uniqueness is created by (label, description) pairs and putting such IDs to the description seems to be a bad idea). best --Herzi Pinki (talk) 12:01, 5 January 2025 (UTC)[reply]

As pointed out in the motivation, as the SOIUSA code only locates a mountain in an alpine subgroup or a sector thereof, it is not a unique identifier and therefore not a certain criterion to identify a duplicate. However, since subgroups or sectors thereof (ridge, small massif) are comparatively small mountain areas, the likelihood of two mountains or summits with the same name having the same SOIUSA code is low.

Further, having a property for this specific code is meant to provide a dedicated place that will ensure that SOIUSA codes will not need to be added to item descriptions to somehow store them.

The huge advantage of a dedicated property is that there is a straightforward way how to retrieve a SOIUSA code, e.g. in SPARQL queries. Due to its hierarchically structure, the SOIUSA code allows to compare e.g. the code of a mountain, which encodes all hierarchy levels down to its subgroup or a sector thereof, with any level of the SOIUSA taxonomy of the Alps. From my perspective, with the various unstructured ways how mountain range (P4552)} and part of (P361) are used it would not be possible to conclude on the entry point into the SOIUSA hierarchy based on these properties. -- Harald Hetzner (talk) 21:42, 5 January 2025 (UTC)[reply]

‎land degradation

Under discussion

Description	The amount of land that is degraded by an object. Mainly for infrastructure projects
Represents	Https://www.wikidata.org/wiki/Q3497778
Data type	Quantity
Domain	geography {Q1071} ecology{Q7150}
Example 1	A69 motorway (Q55681451)→200hc
Example 2	Aéroport du Grand Ouest (Q140205)→200hc
Example 3	Grand projet ferroviaire du Sud-Ouest (Q18331917)→200hc
Allowed units	{Q35852}
Source	https://en.wikipedia.org/wiki/Arable_land#Land_degradation
Planned use	I want to compare the impact of different infrastructure projects on the environment
See also	https://www.wikidata.org/wiki/Wikidata:Property_proposal/forest_cover

Motivation

I need a way to compare the impact of infrastructures projects on the environment. The property would allow to compare the soil degradation. A more generic approach could be "land use", this has been debated here : https://www.wikidata.org/wiki/Wikidata:Property_proposal/forest_cover

– The preceding unsigned comment was added by Petit minion (talk • contribs) at 15:55, March 19, 2025 (UTC).

Discussion

Linguistics

Please visit Wikidata:WikiProject Linguistics for more information. To notify participants use {{Ping project|Linguistics}}

Mathematics

Please visit Wikidata:WikiProject Mathematics for more information. To notify participants use {{Ping project|Mathematics}}

member of sequence or class of number

Under discussion

Description	The number is of a special form or class or member of a sequence
Represents	integer sequence (Q2297602)
Data type	Item
Domain	number (Q11563)
Allowed values	special form, class or integer sequence
Example 1	2 (Q200)→power of two (Q1136880)
Example 2	3 (Q201)→Fermat number (Q207264)
Example 3	4 (Q202)→tetrahedral number (Q975166)
Example 4	5 (Q203)→factorial prime (Q973861)
Example 5	6 (Q23488)→perfect number (Q170043)
Example 6	7 (Q23350)→Euclid number (Q728223)
Expected completeness	always incomplete (Q21873886)
See also	instance of (P31)
Wikidata project	WikiProject Mathematics (Q8487137)

Motivation

There are too many P31 claims on natural numbers, and most of them are used to describe what special form or class the number has, or in other words, what integer sequence the number is a member of. These P31 claims aren't very useful for ontology purposes. A new property helps to clean up P31. It also removes inconsistency related to overcategorization (for example, all Mersenne prime (Q186875) are also prime number (Q49008), should the P31 claim for both be added at the same time? P31 values shouldn't have overcategorization.) Midleading (talk) 15:09, 13 April 2025 (UTC)[reply]

Discussion

Comment I'm not sure how moving P31 claims to a new property is so helpful? The meaning of the new property seems pretty much the same as the current P31. Unless you are proposing to greatly limit P31 for numbers (like Q5 for people)? ArthurPSmith (talk) 02:27, 15 April 2025 (UTC)[reply]
I propose these natural numbers should just have P31 claims with values like natural number (Q21199), integer (Q12503). A subset of natural number (Q21199) that is defined by an integer sequence or special form should not be P31 value. Midleading (talk) 08:05, 17 April 2025 (UTC)[reply]
Comment What is "number"? Does it include quaternion (Q173853) and/or dual number (Q751048)? Why not choose something with a widely accepted precise definition (like integers)? Also, "member of sequence" might be misleading since a sequence is not a class, but a function, and therefore should not be value of P31. 慈居 (talk) 15:52, 16 April 2025 (UTC)[reply]
There are no instances of quaternion (Q173853) or dual number (Q751048) in Wikidata. On the other hand one might want to link from square root of 2 (Q389813) to square root of natural numbers (Q131564913). So the meaning of number could depend on what the subject (which has a Wikidata item) is, and must be instance of number (Q11563). Many special forms are defined by an integer sequence, for example, power of two (Q1136880) can be seen as both a subclass of integers and an integer sequence. Midleading (talk) 08:15, 17 April 2025 (UTC)[reply]
There are no instances of them because no one has created one yet; e.g., dual unit or any of the three quaternion units. To most people $(x^{2})$ is just a polynomial ideal, but some may see it the dual zero. The point is that when you regard some class as a "number class", some may disagree. No ambiguity arises if, instead, you define a property for "complex number type", or "integer type" if you want to refine the property. One could also consider "field/ring element type", etc., whose "number-ness" really depends on your point of view.

Many items about sequences indeed also play role of their ranges, but not in general. Many sequences share the same range, and many subsets of numbers (especially beyond integers) are not characterized by the range of a sequence. No point in causing confusion. 慈居 (talk) 10:01, 17 April 2025 (UTC)[reply]
The meaning of "number" in this property proposal is effectively only a subset of complex number. This is because most abstract algebra structures require a graduate course in Mathematics to understand, and that there doesn't exist a Wikidata item, Wikipedia article or external identifier for an instance of them. We aren't dealing with anything ever constructible in abstract algebra here. Not even any one of the instances of quaternion units you mentioned have a Wikipedia article dedicated to it. The same is also true for sequences of "numbers" in polynomial rings, p-adic numbers and so on. On the other hand, if there is one instance of "number" that is not actually an instance of complex number has a Wikipedia article, and that also is a member of a notable ideal with another Wikipedia article, then I would like to link them. But currently there isn't any, so I don't think it needs more clarification. The same argument also applies to sequences. A Wikipedia article usually describes a class of sequences, or a particular integer sequence in number theory. Therefore it will mostly be used to link an integer or real number to the sequence it is a member of, but if there are notable exceptions, it would be interesting to know. Midleading (talk) 12:22, 17 April 2025 (UTC)[reply]
Complex number is neither less nor more "abstract" than quaternion. And "numbers are complex numbers" only reflects point of view of some people. That's my whole point and I expect modification of your proposal, not defence of it. For now I could only Oppose, with apologies. 慈居 (talk) 13:06, 17 April 2025 (UTC)[reply]

An example which needs to be concerned here would be Thue–Morse sequence (Q1477120), which is a sequence which ranges over 0 and 1. It is more appropriate as a value for part of (P361). 慈居 (talk) 14:00, 17 April 2025 (UTC)[reply]

‎defined for

Under discussion

Description	the subject takes the object as parameter (or parameter tuple)
Data type	Item
Example 1	union (Q185359)defined forfamily of sets (Q739925)
Example 2	dimension of a vector space (Q929302)defined forvector space (Q125977)
Example 3	fundamental group (Q662830)defined forpointed space (Q1419329)

‎partially defined for

Under discussion

Description	the subject takes the object satisfying certain conditions as parameter (or parameter tuple)
Data type	Item
Example 1	function composition (Q244761)partially defined forfunction (Q11348)
Example 2	matrix multiplication (Q1049914)partially defined formatrix (Q44337)
Example 3	supremum (Q215071)partially defined forsubset (Q177646)part of (P361)preordered set (Q78054942)

‎yields as value

Under discussion

Description	the subject has the object as value
Data type	Item
Example 1	union (Q185359)yields as valueset (Q36161)
Example 2	dimension of a vector space (Q929302)yields as valuecardinal number (Q163875)
Example 3	fundamental group (Q662830)yields as valuegroup (Q83478)
Example 4	function composition (Q244761)yields as valuefunction (Q11348)
Example 5	matrix multiplication (Q1049914)yields as valuematrix (Q44337)
Example 6	supremum (Q215071)yields as valueelement (Q379825)part of (P361)preordered set (Q78054942)

Motivation

We already have definition domain (P1568) and codomain (P1571). However, they have as values sets or classes (etc.), and it seems better to avoid creating awkward items such as "the class of vector spaces" or "the class of pairs of functions the domain of the first of which equals the codomain of the second of which".

(Example 1 and 2 for "partially defined for" slightly abuses the proposed property in that the correct value should represent "pair of functions/matrices". We are able to express a pair of distinct values using list of values as qualifiers (Q23766486) but not of equal values.) 慈居 (talk) 15:57, 24 April 2025 (UTC)[reply]

Currently "yields as value" is often stated as instance of (P31) or subclass of (P279) which is rigorously speaking incorrect and have some unexpected implications; e.g., non-empty intersection of function (Q11348) and cardinal number (Q163875). 慈居 (talk) 09:44, 27 April 2025 (UTC)[reply]

The distinction between "defined for" ("yields as value") and definition domain (P1568) (codomain (P1571)) might need further explanation. The subject of definition domain (P1568) can be a function between sets without additional structure, a morphism in a category, and even a higher morphism in a higher category. In the latter cases, merely specifying the elements of the (co)domain would in general not be sufficient. For example, if the morphism is a functor between categories, we need the elements (objects) as well as the morphisms to determine the (co)domain categories.

However, it would indeed be redundant if both "defined for" and definition domain (P1568) were in a single item. I suggest applying conflicts-with constraint (Q21502838). 慈居 (talk) 15:43, 2 May 2025 (UTC)[reply]

Discussion

Comment @慈居: I don't understand the objections stated in the motivation. vector space (Q125977) is right now in Wikidata the class of vector spaces. If there's something in the construction of definition domain (P1568) and codomain (P1571) that makes them not entirely correct I would recommend adjusting their definitions, a discussion on their talk pages (ping people involved in the property creation) would be a good start there. Otherwise it seems to me your first and third proposals are identical to the meaning of definition domain (P1568) and codomain (P1571) respectively. The second proposal regarding "partially defined" I can see as maybe adding something new, where you're trying not to create new items for every possible constraint on the domain of a function. So I think I Weak support "partially defined for" but Oppose the other two. Unless I'm really missing something here? ArthurPSmith (talk) 17:45, 1 May 2025 (UTC)[reply]
Thank you for the comment! The usage instruction suggests a set-of-item (e.g., set of real numbers (Q1174982)) as value while the property proposal and an earlier version of the usage instruction suggests using a normal item (e.g., real number (Q12916)). I guess the edit is made because it is sometimes beneficial to distinguish a "thing" and a set of them; for instance when the things are sets on their own, or when we want the (co)domain to be a set with additional structure, of which the canonical one is not uniquely determined by the elements themselves. 慈居 (talk) 18:27, 1 May 2025 (UTC)[reply]

underlying data

Under discussion

Description	this mathematical structure has these data as part
Data type	Item
Example 1	totally ordered set (Q3054922)underlying dataset (Q36161)
Example 2	totally ordered set (Q3054922)underlying datatotal order (Q369377)
Example 3	group (Q83478)underlying dataset (Q36161)
Example 4	group (Q83478)underlying databinary operation (Q164307)statement is subject of (P805)group operation (Q99839939)
Example 5	group (Q83478)underlying datanullary operation (Q3884029)statement is subject of (P805)identity element (Q185813)
Example 6	group (Q83478)underlying dataunary operation (Q657596)statement is subject of (P805)inverse element (Q338057)

Motivation

This is a property lying between underlying structure(s) (P12322) and has part(s) (P527). underlying structure(s) (P12322) is a stronger property in that it has to reflect (the object part of) a w:faithful functor between appropriate categories. I propose this property because there is now use of this stronger property to mean this weaker property. 慈居 (talk) 16:47, 2 May 2025 (UTC)[reply]

Discussion

@Charp238, I hope you like it! 慈居 (talk) 16:53, 2 May 2025 (UTC)[reply]

Opensofias
Tobias1984
Arthur Rubin
Cuvwb
TomT0m
Physikerwelt
Lymantria
Bigbossfarin
Infovarius
Helder
PhilMINT
Malore
Lore.mazza51
Wikisaurus
The Anome
The-erinaceous-one
Daniel Mietchen
Haansn08
Xenmorpha
John Samuel
Jeremy Dover
Toni 001
Bocardodarapti
Duckmather
HTinC23
fgnievinski
Paul-Olivier Dehaye
uni
Dexxor
慈居
Notified participants of WikiProject Mathematics --Dexxor (talk) 15:34, 5 May 2025 (UTC)[reply]

why not just use has part(s) (P527)? not saying that this has no use but so far it seems a bit dubious to me Uniwah (talk) 17:58, 5 May 2025 (UTC)[reply]

@Uniwah. Thank you for the comment. The reason that I want to refine has part(s) (P527) is that it does not indicate "has part in what sense". "Has part" for a mathematical concept as subject can also mean, say,

a term has a sense (as in Q21199#P527)
a structure has "defining data" (which is standard terminology of mathematics, by the way; the definition of a mathematical concept is typically phrased as "a ... consists of the following data ... satisfying the following conditions ...", and the terms "defining data", "underlying data", etc. are used explicitly throughout mathematical literature; see Mac Lane's Categories for the Working Mathematician for use of "data"; use of other terms is verifiable by google search)
a particular structure has these paticular underlying data (e.g., a 2-category has these as 0-cells, 1-cells or 2-cells)
(edited) notable substructures of structures (e.g., subset of a set, subgroup of a group, etc.)
logical conjunction of some of the above (which is a bad practice, I believe)

Currently I use object of statement has role (P3831) as qualifier to distinguish these meanings but I doubt this is the best practice. 慈居 (talk) 00:30, 6 May 2025 (UTC)[reply]

I'm struggling to see the point of this at the moment. If this is going to be useful, it needs to be absolutely rigorously defined, together with proposed properties for each of the other usages you give, and at the moment I think this is still too wooly. Using object of statement has role (P3831) qualifers on has part(s) (P527) seems like a simple and clear way to implement what you want that doesn't obscure the meaning for more simple-minded users. The Anome (talk) 07:21, 6 May 2025 (UTC)[reply]
- @The Anome Thank you for the comment. (edit: I rephrase my comment, to be brief.) The definitions of the usages of has part(s) (P527) are as follows:
  - A term has a sense: this is a non-mathematical property and has no rigorous definition.
  - A structure has "underlying/defining data": a class of structures ${\mathcal {S}}$ has the class of structures ${\mathcal {D}}$ as underlying data if there exists classes of structures ${\mathcal {D}}_{1},\dots ,{\mathcal {D}}_{m}$ , predicates $P_{1},\dots ,P_{n}$ and $i=1,\dots ,m$ such that $\forall S\colon S\in {\mathcal {S}}\iff (\exists D_{j}\in {\mathcal {D}}_{j}(i=1,\dots ,m)\colon S=(D_{1},\dots ,D_{m})\land (\forall k=1,\dots ,n\colon P_{k}(D_{1},\dots ,D_{m}))\land D=D_{i})$ .
  - A particular structure has these paticular underlying data: suppose ${\mathcal {S}}$ has ${\mathcal {D}}$ as underlying data; then $S\in {\mathcal {S}}$ has $D\in {\mathcal {D}}$ as underlying ${\mathcal {D}}$ -data if $S=(\dots ,D,\dots )$ .
  - (edited) notable substructures of structures: there is no definition of substructures which applies to all structures; there are canonical notion of substructures for particular classes of structures (algebraic substructure for universal algebraic structures, subspaces for topological spaces, submanifolds for ${\mathcal {C}}^{\infty }$ -manifolds, etc.)
  - underlying structure: ${\mathcal {S}}$ has ${\mathcal {D}}$ as underlying structure if ${\mathcal {S}}$ and ${\mathcal {D}}$ are categories (in a canonical way) and there exists a (canonical) faithful functor ${\mathcal {S}}\to {\mathcal {D}}$ ; if ${\mathcal {S}}$ has ${\mathcal {D}}$ as underlying structure then ${\mathcal {S}}$ has ${\mathcal {D}}$ as underlying data; not conversely.
- I'd strongly suggest making these qualifiers, not properties. We can then add a constraint that mathematical object "part-of" relationships should have one (can there be more than one?) of these properties. The Anome (talk) 17:17, 6 May 2025 (UTC)[reply]
  - Yes, there can be more than one; in my opinion qualifiers are better added to separate statements (with the same value) in that case. To clarify, I have listed these usages to explain what has-part can mean in mathematical context; the only one I want a new property for is the underlying-data one. I prefer a new property for this one because there are potentially many properties derived from this one. For example, redundancy of defining data, cf. here. A property for combination of data enough to completely determine the structure, might need an item-requires-statement constraint (Q21503247) which does not work for qualifiers, as far as I know. 慈居 (talk) 17:57, 6 May 2025 (UTC)[reply]

base mathematical structure

Under discussion

Description	base field of this vector space, base ring of this module, pair of base rings for this bimodule, base monoidal category of this enriched category, etc.
Data type	Item
Example 1	abelian group (Q181296)base mathematical structureinteger (Q12503)subject has role (P2868)module (Q18848)object of statement has role (P3831)base ring (Q121217200)
Example 2	quaternionic vector space (Q7269568)base mathematical structurequaternion (Q173853)subject has role (P2868)vector space (Q125977)object of statement has role (P3831)field of scalars (Q99240496)
Example 3	preadditive category (Q2099981)base mathematical structureabelian group (Q181296)subject has role (P2868)enriched category (Q5379515)object of statement has role (P3831)base monoidal category (Q134486094)
Example 4	topological category (Q7825022)base mathematical structurecompactly generated space (Q1738274)subject has role (P2868)enriched category (Q5379515)object of statement has role (P3831)base monoidal category (Q134486094)

Motivation

This property indicates which ring a module is over, which pair of rings a bimodule is over, which monoidal category an enriched category is over, etc, with label "over" chosen among standard wordings. Note that, for instacne, a "module over $R$ " is also phrased as an " $R$ -module", and I prefer that wording, but it doesn't seem applicable to a Wikidata statement anyway.

Note also that this property is to replace the deprecated property of (DEPRECATED) (P642) which is previously used for these purposes. 慈居 (talk)

(Edit history: previous label was over; previously proposed as qualifier property.)

Discussion

Notified participants of WikiProject Mathematics

Comment I think the English label should be more descriptive than "over" to avoid misuse. -wd-Ryan (Talk/Edits) 16:29, 15 May 2025 (UTC)[reply]
@Wd-Ryan The best I can think of is "base mathematical structure" (?). Any suggestion will be appreciated! 慈居 (talk) 08:34, 17 May 2025 (UTC)[reply]
Comment I think I would prefer a relationship like this to be a main value, not a qualifier on subclass of (P279). ArthurPSmith (talk) 18:56, 15 May 2025 (UTC)[reply]
@ArthurPSmith No problem with that with change of label. This can be made a main value property unless confusion arises (perhaps when talking about something like ${\mathcal {M}}$ -module ${\mathcal {V}}$ -category?). 慈居 (talk) 08:20, 17 May 2025 (UTC)[reply]

Material

Please visit Wikidata:WikiProject Materials for more information. To notify participants use {{Ping project|Materials}}

Meteorology

Beaufort scale max

Under discussion

Description	empirical measure describing wind speed based on observed conditions
Aliases	Beaufort, Bf
Represents	wind (Q8094)
Data type	Item
Template parameter	WikiProject Weather observations
Example 1	Cyclone Lothar (Q520286)→whole gale (Q12714822)
Example 2	Q104601398→hurricane force storm (Q20918044)
Example 3	Cyclone Xynthia (Q926626)→hurricane force storm (Q20918044)
Wikidata project	WikiProject Meteorology (Q14943918)

Motivation

(Ajoutez ici vos motivations pour la création de cette propriété et votre signature) – The preceding unsigned comment was added by Bouzinac (talk • contribs) at 16:16, May 3, 2025 (UTC).

Discussion

The property name needs to indicate its recording the peak wind speed for the event. While strictly the Beaufort scale is a number, I can see the merits of linking to the named values on the scale, but the property would need advice on the SPARQL logic to deduce one from the other, as sorting items would be done numerically. How would you handle the values 13-17 on the extended Beaufort scale? How would you prevent people entering storm (Q81054) rather than the correct whole gale (Q12714822). At the same time it would be good to add the speed ranges to each Beaufort value, as they are currently missing.Vicarage (talk) 17:02, 5 May 2025 (UTC)[reply]

That property would have something like in this https://www.wikidata.org/wiki/Property:P8615#P2302 in order to make sure correct items are entered. I don't know how to make Q12714822 ranking 10th on Beaufort scale (to help for the sorting in the queries). Bouzinac ^{💬●✒️●💛} 16:10, 8 May 2025 (UTC)[reply]

Glaciology

All

Nutrition

Wikidata:Property proposal/Natural science

See also

Physics/astronomy

Biology

Embryo Project Encyclopedia ID

Motivation

Discussion

‎breed belongs to taxon

Constraints

Motivation

Discussion

Biochemistry/molecular biology

Chemistry

‎molecular formula

Motivation

discussion

Medicine

Mineralogy

Computer science

Geology

Geography

‎SOIUSA code

Motivation

Discussion

‎land degradation

Motivation

Discussion

Linguistics

Mathematics

member of sequence or class of number

Motivation

Discussion

‎defined for

‎defined for

‎partially defined for

‎yields as value

Motivation

Discussion

underlying data

Motivation

Discussion

base mathematical structure

Motivation

Discussion

Material

Meteorology

Beaufort scale max

Motivation

Discussion

Glaciology

All

Nutrition