Wikidata:Property proposal/Since and Until

"start period" / "end period"Edit

Originally proposed at Wikidata:Property proposal/Generic

   Done: start period (P3415) (Talk and documentation)
Descriptioninitial period in which the statement is valid (including the period-value)
Data typeItem
Example
See alsostart time (P580)

Originally proposed at Wikidata:Property proposal/Generic

   Done: end period (P3416) (Talk and documentation)
Descriptionlast period in which the statement is still valid (including the period-value)
Data typeItem
Example
See alsoend time (P582)
Motivation

Some statements cannot be defined temporally with start time (P580) and end time (P582). That's why I think it will be useful to have two generic properties to own the same meaning of start time (P580) and end time (P582) but the data type is not a time value but an item. See the example to be more clear ★ → Airon 90 15:49, 14 October 2016 (UTC)

Discussion
  •   Support ChristianKl (talk) 17:47, 14 October 2016 (UTC)
  •   Support. I can forsee usage of this for historical figures for when we know things about them relative to events but don't know the date of that event. Thryduulf (talk) 16:35, 15 October 2016 (UTC)
  •   Oppose proposed labels. These are currently aliases of start time (P580) and end time (P582) and they should be the immediate target of these names. Perhaps something like "start time (era)" would be preferable. (Really, I wish that all property types by default had an option to use item instead. There are a lot of similar situations to this.) --Yair rand (talk) 11:48, 27 October 2016 (UTC)
@Yair rand: Sincerely I don't know how to change the labels so choose whatever you want. Keep in mind that this property would not be use just for historical/archaeologic events so era would not be so appropriate.
Later, I will open a discussion in the project chat about a request in Phabricator to add a "fallback type" for every properties which don't require an item as type. -- ★ → Airon 90 07:40, 28 October 2016 (UTC)
What about "start time (item)" and "end time (item)"? Not the most elegant of labels, but we do something similar for things like flag (P163)/flag image (P41) and motto (P1546)/motto text (P1451). - Nikki (talk) 17:34, 29 October 2016 (UTC)
+1. --Yair rand (talk) 15:18, 30 October 2016 (UTC)
  •   Comment See if this would not be best modelled with valid in period (P1264)  . The item linked with this property can have a begin and and time. By WikiProject Reasoning this would be applied as begin and end date of the statement. author  TomT0m / talk page 11:28, 29 October 2016 (UTC)
How would this work for periods with no real begin and end times, like the Clefairy examples in the proposal? I don't want wikidata to fill up with "fake" periods like "first to sixth generation of Pokémon" or "sixth and later generations of Pokémon" just to fill the structural need. valid in period (P1264) fits better for real periods like People's Republic of China (Q148) area (P2046) 6,500,000 km² valid in period (P1264) Ming dynasty (Q9903). Pajn (talk) 11:55, 29 October 2016 (UTC)
@Pajn: It's also a question of redundancy. It's easier to create the item once then use it in several claims just adding one qualifier that using the proposed pair. author  TomT0m / talk page 12:13, 29 October 2016 (UTC)
Also, if the period just has no end time, this makes it still valid up to now, so this is not a problem. author  TomT0m / talk page 12:14, 29 October 2016 (UTC)
@TomT0m: But querying that would be much harder, wouldn't it? For example if you want a list of the types of the Pokémon of the third generation. Either you would have to use all possible ranges that would cover the third generation (infeasible) or you would have to resort to dates which is a hassle because the games were released at different points in time in different regions. Pajn (talk) 12:20, 29 October 2016 (UTC)
@Pajn: I don't think so. First because the existing property can definitely be used two times with items that represents time period with no end time or no begin time, such as "time from the third generation pokemon" for one and "time until the sixth generation pokemon" - which would mean it can be used either as "until" and "since" without having to create items for all the useful combination of begin/end time, second because in a case where a pokemon changes all its properties it may be relevant to ... create an item for each of the version, something like one item for the Clefairy (Q1307681)     of the type fairy-type Pokémon (Q25930814)     and one other item for the Clefairy (Q1307681)     of the type normal-type Pokémon (Q25930498)     linked by replaced by (P1366)   for example. This would make everything clearer and would avoid to qualify all the statements sometimes ... author  TomT0m / talk page 12:36, 29 October 2016 (UTC)
That's certainly a solution, it still requires items just for the structural need which I don't like. But introducing these properties creats two ways to express the same thing which I don't like either and since the amount of items is limited you have convinced med to drop my support Pajn (talk) 12:52, 29 October 2016 (UTC)
  •   Support (see response to comment above) Pajn (talk) 11:55, 29 October 2016 (UTC)
  Weak oppose This should be covered by valid in period (P1264) as per the discussion above Pajn (talk) 12:52, 29 October 2016 (UTC)
  •   Oppose I'd tend to oppose per my comment above : I feel the need is already solved. author  TomT0m / talk page 12:15, 29 October 2016 (UTC) Withdrawing my opposition. But some questions needs to be solved.
  •   Support Even if it's possible to use valid in period (P1264), that seems to me like a workaround for the lack of proper properties to represent the start and end points. I think this is a much cleaner solution than requiring people to create new items for arbitrary periods. - Nikki (talk) 17:34, 29 October 2016 (UTC)
      Support CC0 (talk)
    @Nikki: We don't need this : items defines period of validity by themselves - for example in the sixth generation of Pokemon we only have a creation date and that totally fits with my proposal up-there. This makes me think this proposal is not especially well specified : "until" and "since" what ? The creation date of the subject item ? What about the destruction date ? I'm definitely not convinced this proposal would not require creating items as well for example imagine you want to refer to the end-time of some stuff and that you only have an item for the stuff, you would have to create a dated item "destruction of stuff" to use "until", for example. author  TomT0m / talk page 17:52, 29 October 2016 (UTC)
    I was writing a reply but unfortunately my browser crashed and lost it. The gist of what I was writing was: I think you're focusing too much on dates. Fictional things, like the examples for this proposal, don't have meaningful dates (and you can't reliably use things like publication/broadcast dates, because things are not always published/broadcast in order or on separate days). The relation between things is defined instead by an item and how it's related to other items using properties like series, series ordinal, follows and followed by. - Nikki (talk) 16:57, 18 November 2016 (UTC)
    @Nikki: No it's not defined anywhere, it's left to the user to guess this. This proposal should be written in a way to explicit that. But it's definitely not. author  TomT0m / talk page 17:46, 15 December 2016 (UTC)
    The relation between things being defined by properties is just how Wikidata works, so I don't understand what you want here. If you're asking for this proposal to also describe how the start and end items are linked together, I think that is completely out of the scope of this property proposal and these qualifiers are still useful and valid without that. - Nikki (talk) 19:02, 15 December 2016 (UTC)
    @Nikki: Take the wording of the description of the properties : It defines the item until which the proposition is true => This barely means anything and is way not enough for me. The definition absolutely not refer to any stuffs like preceded by and followed by or any other way to define an arrow of time. And preceded and followed might not even be used to mark a time notion but for example the ranking on a competition ... author  TomT0m / talk page 19:24, 15 December 2016 (UTC)
  •   Support, if I need to use valid in period (P1264) I would have to add thousands of qualifiers. For example: this would be nice to have if you want to define when a character appeared in a television program. And see Otto Flick (Q5743895): I don't want to add 8 qualifiers just to indicate that he was played by that actor for 8 seasons. Sjoerd de Bruin (talk) 16:36, 14 November 2016 (UTC)
  •   Comment Could these properties also be used to describe creation/destruction events, for example: "<island> since <volcanic event>", "<building> until <earthquake event>" or "<caterpillar> until <complete metamorphosis>"? Pixeldomain (talk) 02:01, 17 November 2016 (UTC)
  • @Airon90, ChristianKl, Thryduulf, Yair rand, Nikki: @TomT0m, CC0, Sjoerddebruin, Pixeldomain: After reading all the comments, I think these properties are ready for creation, however in order to keep consistency with start time (P580), end time (P582), and valid in period (P1264), the proposed main labels for these properties are start period and end period. If there are no objections, I will proceed to create them in the next days.--Micru (talk) 15:54, 15 December 2016 (UTC)
    Those suggestions seem to have the same problem as the "start era" suggestion above (I wouldn't consider a TV episode (which is one of the example usages) a "period"), so I still think the labels I suggested above ("start time (item)" and "end time (item)") would be better. Labels can always be changed though... - Nikki (talk) 16:29, 15 December 2016 (UTC)
    Certainly that's an issue, but I don't see how your proposal would help. I wouldn't consider a TV episode to be a "time" either, so "period" is just as good on that front, but also helps disambiguate. --Yair rand (talk) 19:57, 15 December 2016 (UTC)
  Comment I propose to change the description of until : last period in which the statement is still valid (including the period-value).
  Question I suppose and untold - but obvious - assumption is that there is a sequence of items that represents a sequence of events like "generation of pokemon sequence" for example. Should we use the qualifier series search to qualify the statements to explicit the series at sake here ? The rationale is that for TV series episode, for example, an episode can be used in several series items, like the item of the season and the item of the whole TV series. In that case, the series item can be either one and the sequence of items may not be obvious. And over could be the sequence of time in the story, that the series may not diffuse chronologically, like Star Wars. My proposition would be to qualify the statement to make explicit the series such that the followed by or preceded by statement could be chosen correctly. The example would become