I happened to stumble upon this: List of other mathematics resources for the FAQ. Probably the post is already obsolete - the last activity is 6 years ago.

Anyway, uniquation is mentioned there. Has anybody seriously used this search engine to search in math.SE? How good is it?

@MartinSleziak I remember once I emailed the author of (uni)quation (Denis Rystsov <rystsov.denis@gmail.com>), telling him I am doing a math search engine (when Approach0 is called "Cowpie" and is still math-only search engine), he replied and wrote "I've checked your search engine and was surprised. It works better then many others".

BTW. Cowpie is the early prototype of Approach0, and is the version I write as a course project.

It has been almost two years when he send me this email.

I think uniquation is great in some perspectives, first it combines similar formulas (in my terms, formulas with different matching depth) into one search result, each search result in uniquation represents a different level of match with the query, it is like the idea of "faceted search" in terms of fulltext search engine.

second, it is really a pioneer in math search engines, also being considered very fast given the time when it is published.

Uniquation seems to return also some results from Math.SE and MathOverflow, which is why I have mentioned it in an answer to the meta.MO post.

Perhaps that might have contributed to a bit more views. (I assume that if the question gets to +3, which is threshold for including into community-bulletin, then the questions might get more views, being displayed in the main site in the CB.)

Since I am mentioning other search engines, in some past similar questions, also SearchOnMath have been mentioned. But it seems it does not search on Math.SE and MO: searchonmath.com/…