@inproceedings{santos-etal-2026-lexiris,
    title = "{L}ex{I}ris-pt and {L}ex{B}ert-pt: Specialized Sentence Embeddings for Legal Similarity in {B}razilian {P}ortuguese",
    author = "Santos, Willgnner Ferreira  and
      Viana, Jo{\~a}o Gabriel Grandotto  and
      J{\'u}nior, Ant{\^o}nio Pires de Castro  and
      Trindade, Fernando Ribeiro  and
      Silva, N{\'a}dia F{\'e}lix Felipe da",
    editor = "Souza, Marlo  and
      de-Dios-Flores, Iria  and
      Santos, Diana  and
      Freitas, Larissa  and
      Souza, Jackson Wilke da Cruz  and
      Ribeiro, Eug{\'e}nio",
    booktitle = "Proceedings of the 17th International Conference on Computational Processing of {P}ortuguese ({PROPOR} 2026) - Vol. 1",
    month = apr,
    year = "2026",
    address = "Salvador, Brazil",
    publisher = "Association for Computational Linguistics",
    url = "https://preview.aclanthology.org/ingest-dnd/2026.propor-1.53/",
    pages = "540--550",
    ISBN = "979-8-89176-387-6",
    abstract = "This work presents and evaluates two specialized sentence embedding models for the Portuguese legal domain, LexIris-pt and LexBert-pt, obtained through supervised fine-tuning of BERT-based models using pairs of initial petitions. We propose a comparative evaluation protocol along three fronts: (i) zero-shot inference with pretrained embeddings, (ii) supervised fine-tuning on these pairs, and (iii) vector retrieval with incremental clustering over a corpus of 20,000 initial petitions. The results show that fine-tuning consistently increases correlations with reference scores and improves performance in vector retrieval; additionally, the vector retrieval stage indicates that the metric configured in the index (cosine similarity or inner product) can change the granularity of the partitioning under a fixed threshold, reinforcing the need for joint calibration among the encoder, metric and threshold. After auditing by specialists from the partner institution, LexIris-pt and LexBert-pt were operationally adopted to support the screening and organization of repetitive claims and predatory litigation."
}