While these types of blogs might not be revolutionary, they're still useful to people new to the subject who might just be getting into search or are having to implement lite search functionality into their applications.

I'm actually working on an application now where the initial spec called for "search" and it was implemented as exact token matching. A bug was immediately filed because searches for "wlk", "walk", and "walk event" all returned different results.

Have you often seen adversarial training used for sequence labeling to improve generalization across domains? The LSTM-CRF model appears to be the same model proposed by Lample et al (2016). I’d agree that it is common now to use that architecture.