Maybe it could be possible to include a advanced mode in which after combining two or more tags the user can change the relationship amongst them and the files get sorted in-out according to the new settings.
I explain better. When you combine the tags 2003 and 2004 the line appears on top:
"You are now viewing files in tabble 2003 and in tabble 2004".
I suggest to change the "and" part with a dropbox or something more fancy that could change it to other logic operators such "OR" and "NOT". The change could allow combinations as "You are now viewing files located in tabble 2003 or in tabble 2004" for the OR case and "You are now viewing files located in tabble 2003 not present in tabble 2004".
I know the terminology used can be confusing to those that didn't study set theory but it makes sense, probably makes more sense if avaiable only in "expert mode" so not to disconfort casual users of the program.



