Dependency Syntax and Universal Dependencies › Summary

Dependency syntax represents grammatical relations as directed, labelled arcs between syntactic words. In the basic UD representation every word has one incoming arc when artificial node 0 is included, exactly one word has HEAD=0, and the graph is connected and acyclic. A valid graph is not automatically a correct linguistic analysis.

UD normally connects content words directly and attaches related function words to them. Bound morphology remains a property of a word, whereas a separate case-marking word can appear as a dependency node. Shared inventories increase cross-linguistic parallelism without erasing language-specific syntax or annotation conventions.

Projectivity connects dependency structure to linear word order: every word between a head and dependent must be dominated by that head. In our relative-clause example, yesterday violates that condition for the arc from dog to Terrier. The other intervening words belong to dog's subtree. Including the artificial root arc matters when using a crossing-arcs drawing as the test.

CoNLL-U separates word forms, lemmas, POS tags, morphology, basic heads and labels, enhanced dependencies, and miscellaneous annotations. Its integer words, multiword-token ranges, and decimal empty-node identifiers serve different purposes. The bounded reader in this chapter preserves ten fields for basic integer-ID records and explicitly rejects the other record types.

The executable examples read three hand-written sentence analyses, validate their basic-tree constraints, draw two of the trees, and detect projectivity violations. They inspect annotations rather than predict them. The next chapter turns to algorithms that infer structures. The following chapter examines structured prediction and parsing evaluation.