AUTOMATIC INDEXING IN THE AGE OF LANGUAGE MODELS
Keywords:
automatic indexing, indexing evaluation, language modelsAbstract
Bibliographic databases and institutional repositories incorporate millions of documents annually, making exclusively manual processing unfeasible. In this context, indexing is essential for information organization and retrieval. This research compares three paradigms of automatic indexing under controlled vocabulary: a heuristic system based on rules and terminological recognition, a supervised machine learning approach for multilabel classification, and a large language model approach implemented in a hybrid pipeline combining lexical and semantic retrieval. A corpus of more than 9,500 documents in Agriculture was constructed, including 8,000 documents for training and three test sets with 500 documents each. The evaluation used reference standards derived from the AGRICOLA database, obtained by replicating search strategies and manually aligning the indexing. Indexing was restricted to the controlled vocabulary of the National Agricultural Library, previously normalized and represented in textual and vector formats. The results show that comparison among the approaches cannot be reduced to technological substitution: each paradigm responds differently to the requirements of automatic indexing. In the investigated corpus, hybrid solutions combining terminological control, textual retrieval, and semantic inference appear more suitable for exploring the potential of language models than using them as self-sufficient indexers.