Hi Thomas,
On 22.04.2015 20:06, Thomas Douillard wrote:
Hi, there is items about Wikibase data model in Wikidata (created by me,
but not only)
If I understand correctly, they could be cited in the semantic web as
https://www.wikidata.org/entity/Q19798647
"No value" is exactly that: not a value. It should not be confused with
a (definite) value that is used with claims (as the item description
seems to suggest). The reason why we introduced "no value" was to be
able to say this without resorting to a "special value" to represent this.
You can also find some rationale about this in our article "Wikidata: a
free collaborative knowledgebase" (see
https://ddll.inf.tu-dresden.de/web/Article4002/en). Basically, the main
point is that, if you are querying for two people with a common child,
you wouldn't want to get pairs of people who both have "novalue" as a
value for "child". The same is true for "some value" (sometimes referred
to as "unknown value") -- again, if this would be a definite "special"
value, and be treated like a value in queries, it would lead to wrong
results.
Cheers,
Markus
(If they are kept /o\)
Tom²
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