Just like in English, Portuguese nouns don't inflect according to grammatical case. However, in English, traces of a case system (nominative, genitive, dative, accusative) are found in question words like whose (gen.) or whom (dat.) or in personal pronouns like I (nom.) or my (gen.) etc.
In Portuguese, there's eu, me and mim. Are there question words for whose or whom (which don't use de, para, etc.)?
Where can I see other remnants of a case system in Portuguese?