Find the most precise common superclasses between two items

Question

I would like to find the first common superclass(es) between several Wikidata entities.

Let's take a bridge and a cemetery. What is their "smallest" common superclass?

A bridge is a subclass of "architectural structure".
A cemetery is a subclass of "place of worship", which is a subclass of "architectural structure".

---> Their most specialized common class is "architectural structure".

This Sparql query is close to the solution :

SELECT ?classe ?classeLabel WHERE {

wd:Q12280 wdt:P279* ?classe .
FILTER  EXISTS { wd:Q39614 wdt:P279* ?classe .}

 SERVICE wikibase:label { bd:serviceParam wikibase:language "[AUTO_LANGUAGE],en". }

}

Problem: it returns all common classes between both items, not just the first ones. How could I filter the answer to get what I want?

Well, your query doesn't reflect in any sense the definition of *Least Common Subsumer*(LCV) You're simply querying for all superclasses `A` of `bridge` and `for all superclasses `B` of `cemetery` and then you return classes contained in `A` and `B`. You should check the definition of LCS and see which other condition is necessary. — UninformedUser, Dec 26 '17 at 16:42
Least Common Subsumer is certainly the phrase I was looking for, but I did not know it existed and could not search Google effectively. — Ettore Rizza, Dec 26 '17 at 16:46
Here we go: `SELECT ?classe ?classeLabel WHERE { wd:Q12280 wdt:P279* ?classe . wd:Q39614 wdt:P279* ?classe . filter not exists { ?otherClass wdt:P279 ?classe ; ^wdt:P279* wd:Q12280, wd:Q39614 . } SERVICE wikibase:label { bd:serviceParam wikibase:language "[AUTO_LANGUAGE],en". } }` — UninformedUser, Dec 26 '17 at 16:47
Oh, thank you very much! But could you publish this query in an answer, so I can accept it? — Ettore Rizza, Dec 26 '17 at 16:49

score 0 · Accepted Answer · answered Jan 23 '18 at 12:48

If this question is of interest to someone else, here is the SPAQL query I finally use to get the Least common subsumers of more than two items. This is a mix between @AKSW response in comments and the answer to that previous question on SO.

SELECT ?lcs ?lcsLabel WHERE {

    ?lcs ^wdt:P279* wd:Q32815, wd:Q34627, wd:Q16970, wd:Q16560 .
    filter not exists {
    ?sublcs ^wdt:P279* wd:Q32815, wd:Q34627, wd:Q16970, wd:Q16560 ;
          wdt:P279 ?lcs .
      }

      SERVICE wikibase:label { bd:serviceParam wikibase:language "[AUTO_LANGUAGE],en". } 
    }

Try it.

Find the most precise common superclasses between two items

1 Answers1