Subordstokens

Subordstokens are a category of tokens used in computational linguistics and natural language processing to denote subordination within sentences. The term encompasses tokens that introduce or mark subordinate clauses, including subordinating conjunctions such as although, because, and since; complementizers like that and whether; and other markers that attach dependent clauses to a main clause. In some definitions, subordstokens also include certain relative pronouns and particles that contribute to the subordination relationship.

In processing pipelines, subordstokens can be represented as explicit tokens or as attached metadata on existing tokens. A tokenizer or parser might label each token with a subordination flag or insert a dedicated subord token at the start of a subordinate span. This explicit signaling supports the learning of hierarchical structure and long-distance dependencies in models.

Applications of subordstokens include dependency parsing, constituency parsing, machine translation, and information extraction. Recognizing subordinate clauses can improve semantic interpretation, antecedent resolution, and translation fidelity, especially in languages with rich subordination or flexible word order.

Challenges include cross-linguistic variation, ambiguity in markers, and inconsistent annotation schemes across corpora. There is no universal standard for subordstokens, and different frameworks may adopt different sets of markers or labeling conventions.

See also: Subordination, Complementizer, Subordinate clause, Dependency grammar, Universal Dependencies, Natural language processing.