Dense embedding for passage retrieval: training bi-encoders with contrastive learning and negative sampling strategies.

Fundamentals of passage retrieval for open-domain QA, covering sparse embedding, TF-IDF, and similarity search in vector space.

Solution for Baekjoon 12100 (2048 Easy) using brute-force simulation with block merging and four-directional movement.

Generation-based MRC using seq2seq models like BART: comparison with extraction-based approaches, preprocessing, and decoding strategies.

Extraction-based machine reading comprehension: span prediction with BERT, preprocessing, fine-tuning, and post-processing.

Survey of post-BERT NLP models including XLNet, RoBERTa, BART, T5, Meena, and controllable language models like PPLM.