Comment 3 for bug 1931566

Hey Alejandro, I'm looking into this right now. The regex you provided would not usually work on a regex engine because most engines, including the standard python one, only allows for fixed-length backreferences, while this part of your regex "(?<!->\w+mente[. ].+)" is not fixed-length due to the +. However, I am looking into this in more detail because the regex "^(?!->\w+mente[. ].+).*\d\.\ adv\.(?!.*desus\.)(?!.*vulg\.)" should work and do what you intend, and does work in all the regex engines I have tested, but returns no results in calibre, and furthermore calibre uses a non-standard regex engine that should actually work with your original regex.