stanfordnlp/CoreNLP · error · ParseException

Unknown relation

Error message

Unknown relation 

What it means

GraphRelation.createRelation throws java.text.ParseException when the relation symbol (reln) is not one of the known Semgrex relation operators (>, >++, <, <<, ==, ~, etc.). The symbol is checked against a whitelist via isKnownRelation before dispatching to the relation class.

Solutions

1. Correct the relation symbol to a valid Semgrex operator (>, <, <<, >>, ==, ~, <<#, etc.)
2. Check the Semgrex documentation for the supported relation list
3. If porting from Tregex, translate each relation to its Semgrex equivalent

Example fix

// before
String pattern = "{word:dog} => {word:cat}";
// after
String pattern = "{word:dog} > {word:cat}";

Set<String> known = Set.of(">",">>",">++","<","<<","<<#",">>","<<:",">>:","==",".","~");
if (reln != null && !known.contains(reln)) throw new IllegalArgumentException("Unknown relation " + reln);

try { GraphRelation r = GraphRelation.createRelation(reln, type, name, edgeName); } catch (ParseException e) { log.error("Unknown Semgrex relation '" + reln + "'"); }

When it happens

Trigger: Calling GraphRelation.createRelation with an unrecognized reln string, e.g. a typo like '=>', 'gov', or an operator from a different grammar (Tregex-style) pasted into a Semgrex pattern.

Common situations: Hand-written Semgrex queries with mistyped relation operators; porting Tregex patterns to Semgrex without translating relations; config or query files edited manually.

Related errors

• GraphRelation had both = and ~ set, but the names were…
• Use of & in semgrex patterns is now illegal. It is…
• Parsing failed. Error:
• Couldn't parse + json
• Invalid txtGraph

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/3e37d0ed3decfe9f. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/semgraph/semgrex/GraphRelation.java:1460

            reln.equals(">>") || reln.equals("<<") ||
            reln.equals("<>") ||
            reln.equals("@") || reln.equals("==") ||
            reln.equals("$+") || reln.equals("$++") ||
            reln.equals("$-") || reln.equals("$--") ||
            reln.equals(".") || reln.equals("..") ||
            reln.equals("-") || reln.equals("--") ||
            reln.equals(">++") || reln.equals(">--") ||
            reln.equals("<++") || reln.equals("<--"));
  }

  public static GraphRelation getRelation(String reln,
                                          String type,
                                          String name,
                                          String edgeName) throws ParseException {
    if (reln == null && type == null)
      return null;
    if (!isKnownRelation(reln)) {
      throw new ParseException("Unknown relation " + reln);
    }
    switch (reln) {
      case ">":
        return new GOVERNOR(type, name, edgeName);
      case ">++":
        return new GOVERNOR_RIGHT(type, name, edgeName);
      case ">--":
        return new GOVERNOR_LEFT(type, name, edgeName);
      case "<":
        return new DEPENDENT(type, name, edgeName);
      case "<++":
        return new DEPENDENT_RIGHT(type, name, edgeName);
      case "<--":
        return new DEPENDENT_LEFT(type, name, edgeName);
      case "<>":
        return new CONNECTED(type, name, edgeName);
    }
    if (edgeName != null) {

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