11:28 AM
@MartinR @Sil Since you asked for the filter feature before, I want invite you to have a very first test on the updated system.
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So here is the features:
(1) \exact specifier for symbols: approach0.me/search/…
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(2) to search for posts of some tags: approach0.me/search/…
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(3) to search certain keywords in only title field: approach0.me/search/…
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(4) to limit data source to MSE: approach0.me/search/… and limit data source to AoPS approach0.me/search/…
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(5) to use NOT clause to filter things: approach0.me/search/…
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wait a minute, i need to restart the server...
I find one query can crash it, but for now just test those examples. Let me know if they work as you expected.

11:47 AM
@WeiZhong Great! I'll surely test that as soon as an opportunity arises.

this is a temporary site for test purpose only, and it has only thousands of posts in the index. I will index full data if everything is working. BTW. you should notice now the search engine do not differentiate \sin and (malformed) sin anymore.
@MartinR thanks, I will put it there for a while, and please send in your comment later.
i am going to leave for dinner now, you may be unlucky and crash the server because there is a bug i find just now, but it should handle most of the queries. i will back soon after a while.

12:42 PM
@WeiZhong Played with it for a bit and so far so good!
One has to be careful though, I have omitted "," once and the filter did not apply (even though it looks graphically the same in the top box: approach0.me/search/…
I guess it would be too much work to not show the filters in the top box if the comma is missing?

12:57 PM
@Sil Good catch! I will fix that.

1:50 PM
@WeiZhong: Is the initial OR required? It seems that it works without.
Generally, how is a sequence of OR/AND/NOT clauses evaluated?

@MartinR nope, it is the default.
@MartinR OR basically allows omitting the keyword, AND requires the keyword to occur, NOT prohibits the occur of keywords.

7 hours later…
9:29 PM
@Sil I've fixed that, it should work now (refresh your browser).

9:42 PM
Also, I have fixed the crash mentioned earlier. The crashed query is about ignoring redundant parentheses under fraction, now it is working:
(6) Ignore redundant parentheses under fraction: https://approach0.me/search/?q=OR%20content%3A%24%5Cleft(1%2B%5Cfrac%7B1%7D%7B(n)%7D%5Cright)%5En%24&p=1

Looks good :)

(7) And... now it also supports NOT math clause! approach0.me/search/…
NOT math clause does not simply exclude a keyword, it sets up threshold for math clause and only exclude posts which contain the math keywords with greater-than-threshold similarity. This one is very tricky, and i've spent some time to get it right. Now I am happy it seems working.