need help understanding mudaf and mudaf ialyhi

format_quote Originally Posted by nutty

From my understanding mudaf is to be possessed while mudaf ilahi is the possessor.

Mudaaf/mudaaf ilayhi constructions generally denote possession, meaning something of something, or someone's something, eg كِتَابُ حَامِدٍ Hamid's book, or كُرْسِيُّ الْمُدَرِّسِ "the teacher's chair", or "the chair of the teacher".

format_quote Originally Posted by nutty

e.g baytul allah - Baytul bein mudaf and allah being mudaf ilahi. Allah is the possessor of the house.

Here bayt is the mudaaf, and Allah is the mudaaf ilayhi, together being baytullah, meaning, "the house of Allah", or "Allah's house". It doesn't linguistically translate as "Allah is the possessor of the house", that would be something along the lines of "Allahu maalik al-bayt".

format_quote Originally Posted by nutty

now in rabbul aalameen - rabbul is the mudaf which mean that it is possessed by the mudaf ilahi which is aalameen - world?..that doesnt make sense to me

Here Rabb is the mudaaf, and al-aalameen is the mudaaf ilayhi, meaning "Lord of the Worlds". It does not mean that the worlds physically possess the Lord, it means the Lord of the worlds. The mudaaf/mudaah ilayhi construction is something of something, or someone's something but, in English, to keep it short, mudaaf/mudaaf ilayhi is called possession, the mudaaf grammatically being called the possessor and the other word gramatically being called the possessed. It doesn't necessarily however mean that literally, one thing physically possesses the other.

format_quote Originally Posted by nutty

another similar one - rabbi nas - Surah Nas

Meaning the Lord of mankind.

format_quote Originally Posted by nutty

Should aalameen be mudaf and rabbul be mudaf ilahi...because rabbul is possessor of the universe..

No. See above.

While mudaaf mainly shows possession between two nouns, there also other words that function as mudaaf, and the noun that follows them being mudaaf ilayhi, eg تَحْتَ meaning 'under', eg تَحْتَ الْسَّرِيْرِ meaning "under the bed". Tahta here is grammatically mudaaf, and as-sareeri is mudaaf ilayhi, and it is called a possessive construction (mudaaf/mudaaf ilayhi) even though in the meaning there is no possession.

I hope that didn't make it more complicated.