Can you please help with my confusion with the following:
1. The Prepositional case of adjectives is formed from the Nominative case of adjectives.
2. Prepositional case of adjective "russian" is "русском" ending in "-om" asssuming that nominative case was hard stem.
3. Nominative case of adjective russian is "русский" which in its form seems to be soft stem (at least for me maybe I am wrong)
, I am wondering why prepositional case of adjective "russian" is "русском".
My only theory would be that because nominal case takes only "ий" instead of "ый" because of the 7 letter spelling rule, so the prepositional case "remembers" the original stem hided by the spelling rule in the nominative case and use that for forming the prepositional case.
Which in turn results a hard stem prepositional case forming even if the nominative case in itself at first sight seemed to be soft stem.
Can someone please confirm that my understanding is correct or do I misunderstand something and/or there is another explanation?
Thank you for your help in advance