«Sławnymi», my dear false friend :)) /in Russian it's not 'famous', but rather 'good, nice'; except for some fixed pairs like «славными победами», then it's 'famous, glorious'/ PS: BTW, am I right to understand that Polish 'artysta' is more narrow than English 'artist' and includes mostly people like painters but not like singers?
My first thought would be a painter, but in fact the meaning seems quite wide. It applies for singers as well.
So after the verb ''byc'' I should use Instrumental case, right? And in negative statements should I use genitive?
Mostly yes, you do use Instrumental after "być". In negative statements as well.
Because the rule for negative=Genitive works when in the positive sentence there was Accusative.
So.... If in the phrase "Lubię wodę", the word "woda" is in the Accusative case, the negative phrase would be "Nie lubię wody" with the word "woda" in its genitive. Naprawdę?