ner

Both tag sequences, but one is generative and one is discriminative, and that difference decides whether you can throw in overlapping features. Here is the comparison that shows you know the modeling tradeoff, not just the acronyms.

Query understanding is the front end of search that turns a raw query into structured intent. Get it wrong and even a perfect index returns garbage. The signal is the pipeline and how you measure it. Here is the design.

Detection is imperfect, so the strong answer is layered: regex with checksums for structured PII, ML/NER for the unstructured PII regex cannot see, and a frank account of why you never rely on redaction alone. Here is the answer.