global page title with default value
can filter by medium for some artists via URL param, like picasso/ceramics
upon creating page title, if there is not a match for that particular filter on that particular artist, then forward to artist page. i.e. pablo-picasso/ceramics is OK, but pablo-picasso/dogs forwards to artist page. Likewise, yaacov-agam/ceramics forwards to artist page too because that is not a valid filter for Agam.