Nested named entity recognition identifies entities contained within other entities, but requires expensive multi-level annotation. While flat NER corpora exist abundantly, nested resources remain scarce. We investigate whether models can learn nested structure from flat annotations alone, evaluating four approaches: string inclusions (substring matching), entity corruption (pseudo-nested data), flat neutralization (reducing false negative signal), and a hybrid fine-tuned + LLM pipeline. On NEREL, a Russian benchmark with 29 entity types where 21% of entities are nested, our best combined method achieves 26.37% inner F1, closing 40% of the gap to full nested supervision. Code is available at https://github.com/fulstock/Learning-from-Flat-Annotations.

This study examines the capability of LLMs to predict emotional ratings of Russian words by comparing their assessments with both native speakers’ ratings and expert evaluations. The research utilises two datasets: the ENRuN database containing associative emotional ratings of Russian nouns by native speakers, and RusEmoLex, an expert-compiled lexicon. Various open-source LLMs were evaluated, including international models (Llama-3, Qwen 2.5), Russian-developed models, and Russian-adapted variants, representing three parameter scales. The findings reveal distinct patterns in model performance: Russian-adapted models demonstrated superior alignment with native speakers’ ratings, whilst model size was not a decisive factor. Conversely, larger models showed better performance in matching expert assessments, with language adaptation having minimal impact. Emotional or sensitive lexis with strong connotations produce a more substantial human-model gap.