Skip to content

Querying in zelph

zelph provides powerful querying capabilities directly in its scripting language and interactive CLI. Queries allow you to search the semantic network for matching patterns, supporting variables, multiple conditions, and integration with inference rules. This page covers general queries first (applicable to any domain), followed by Wikidata-specific examples.

Queries are statements that contain variables (single uppercase letters) but no => (which would make them rules). They are evaluated immediately without needing .run, though inference can expand the graph beforehand to reveal more matches.

Key Features

  • Variables: Single uppercase letters (A-Z) or words starting with an underscore _, scoped to the query.
  • Multi-Conditions (Conjunctions): Use comma conjunctions inside parentheses, e.g. (cond1, cond2), or the explicit form (*{(cond1) (cond2)} ~ conjunction).
  • Wildcards: Use variables for subjects, relations, or objects (e.g., X R Y matches any triple).
  • Inference Integration: Automatically performed after each command (also see command .auto-run).
  • Output: Matches are printed with bound values. No matches: Just the query echoed.
  • Limitations: No multi-line queries.

General Queries

These examples use a simple geography graph. Load them in zelph (.lang zelph mode) for testing:

zelph> Berlin "is capital of" Germany
zelph> Germany "is located in" Europe
zelph> Europe "has part" Germany
zelph> (X "is capital of" Y, Y "is located in" Z) => (X "is located in" Z)
 Berlin   is located in   Europe  ⇐ {( Germany   is located in   Europe ) ( Berlin   is capital of   Germany )}
zelph>

Single-Condition Queries

Basic pattern matching.

  • Find capitals: X "is capital of" Y
    Output:
X  is capital of  Y
Answer:  Berlin   is capital of   Germany
  • Find locations in Europe: A "is located in" Europe
    Output (post-inference): 
    A  is located in   Europe
Answer:  Germany   is located in   Europe
Answer:  Berlin   is located in   Europe

Multi-Condition Queries

Combine for intersections.

  • Capitals in Europe: X "is located in" Europe, X "is capital of" Y
    Output:
Answer: {( Berlin   is capital of   Germany ) ( Berlin   is located in   Europe )}

Note: In this example we use the comma , syntax sugar for conjunctions. The fully explicit form is (*{(X "is located in" Europe) (X "is capital of" Y)} ~ conjunction).

Wikidata-Specific Queries

For Wikidata, switch to .lang wikidata after loading a dump (.load path/to/dump.json or .load cached.bin). Queries use Q/P IDs or names (if set). Examples from paleontology (e.g., Brontosaurus Q3222766).

Single-Condition Queries

  • Instances of fossil taxon: X P31 Q23038290
    Output: Many answers, e.g., Answer: Q3222766 P31 Q23038290 (Brontosaurus).

  • Parent taxa: X P171 Q3222766
    Output: Taxa with Brontosaurus as parent (if any).

Multi-Condition Queries

Combine for targeted searches.

  • Fossil taxa in genus rank: (*{(X P31 Q23038290) (X P105 Q34740)} ~ conjunction)
    Output: Matches like Brontosaurus/Apatosaurus.

  • Synonyms with parent taxon: (*{(X P460 Q14326) (X P171 Q2544161)} ~ conjunction) (Apatosaurus synonyms in Diplodocidae)
    Output: 

    {(X  P171   Q2544161 ) (X  P460   Q14326 )}
Answer: {( Q3222766   P171   Q2544161 ) ( Q3222766   P460   Q14326 )}
    Since Q3222766 is Brontosaurus, this answer means "The parent taxon (P171) of Brontosaurus is Apatosaurinae (Q2544161), which is said to be the same as Apatosaurus (Q14326).

Tips and Advanced Usage

  • Debugging: Use .node, .out, .in to inspect before querying.
  • Patterns: Fixed parts in quotes if spaces; variables anywhere.
  • For complex logic, define rules first, then query the inferred graph.

See Rules and Inference for synergy with queries.