Hierarchy Traversal - SPARQLqueries

Understanding Wikidata's Class System

Wikidata organizes knowledge using two key properties:

Property	Meaning	Example
`wdt:P31`	instance of	Python (P31) programming language
`wdt:P279`	subclass of	art museum (P279) museum

The combination wdt:P31/wdt:P279* means "is an instance of something that is (directly or through subclasses) a specific type."

Property Path Syntax

Syntax	Meaning	Use Case
`p*`	Zero or more	Any depth (including self)
`p+`	One or more	At least one step
`p?`	Zero or one	Optional single step
`p{n}`	Exactly n	Fixed depth
`p{n,m}`	Between n and m	Limited depth range
`p/q`	Sequence	p then q
`p\|q`	Alternative	p or q
`^p`	Inverse	Reverse direction

The Classic Instance-Subclass Pattern

Find All Programming Languages (Including Subtypes)

Run ↗

SELECT ?lang ?langLabel ?type ?typeLabel
WHERE {
  # Instance of programming language OR any subclass
  ?lang wdt:P31/wdt:P279* wd:Q9143 .

  # Get the specific type for display
  ?lang wdt:P31 ?type .

  SERVICE wikibase:label {
    bd:serviceParam wikibase:language "en" .
  }
}
LIMIT 50

Pattern wdt:P31/wdt:P279* — The foundational hierarchy pattern

Find All Museums (Art, History, Science, etc.)

Run ↗

SELECT ?museum ?museumLabel ?typeLabel ?countryLabel
WHERE {
  ?museum wdt:P31/wdt:P279* wd:Q33506 ;  # museum
          wdt:P31 ?type ;
          wdt:P17 ?country .

  SERVICE wikibase:label {
    bd:serviceParam wikibase:language "en" .
  }
}
LIMIT 50

Pattern Domain: Cultural Heritage

Exploring Class Hierarchies

Show Subclasses of Programming Language

Run ↗

SELECT ?class ?classLabel ?parentLabel
WHERE {
  # Find all subclasses of programming language
  ?class wdt:P279+ wd:Q9143 .

  # Get direct parent for tree visualization
  ?class wdt:P279 ?parent .

  SERVICE wikibase:label {
    bd:serviceParam wikibase:language "en" .
  }
}
ORDER BY ?parentLabel ?classLabel

Pattern Visualize: #defaultView:Tree

Administrative Hierarchy (City to Country)

Run ↗

SELECT ?place ?placeLabel ?parentLabel
WHERE {
  VALUES ?city { wd:Q90 }  # Paris

  # Traverse P131 (located in administrative unit)
  ?city wdt:P131* ?place .
  OPTIONAL { ?place wdt:P131 ?parent . }

  SERVICE wikibase:label {
    bd:serviceParam wikibase:language "en" .
  }
}

Pattern Domain: Urban | P131 hierarchy

Limited Depth Traversal

Subclasses Within 3 Levels

Run ↗

SELECT ?class ?classLabel
WHERE {
  # Limit to 1-3 steps (not unlimited)
  ?class wdt:P279{1,3} wd:Q33506 .  # museum

  SERVICE wikibase:label {
    bd:serviceParam wikibase:language "en" .
  }
}

Pattern Bounded depth prevents runaway queries

Inverse Traversal

Find Parent Classes (Going Up the Hierarchy)

Run ↗

SELECT ?parent ?parentLabel
WHERE {
  # Start from "scripting language" and go UP
  wd:Q187432 wdt:P279+ ?parent .

  SERVICE wikibase:label {
    bd:serviceParam wikibase:language "en" .
  }
}

Pattern Finds: scripting language → programming language → formal language → ...

Alternative Paths

Match Multiple Relationship Types

Run ↗

SELECT ?entity ?entityLabel
WHERE {
  # Match P31 OR P279 (instance or subclass)
  ?entity (wdt:P31|wdt:P279) wd:Q9143 .

  SERVICE wikibase:label {
    bd:serviceParam wikibase:language "en" .
  }
}
LIMIT 30

Pattern p|q — Alternative paths

Common Pitfalls

Mistake	Problem	Solution
`?x wdt:P279* ?y`	Unbounded on both ends	Always fix one end
`wdt:P279*` without `wdt:P31`	Matches classes, not instances	Use `wdt:P31/wdt:P279*`
Deep hierarchies	Timeout on large trees	Use depth limits `{1,5}`