Ḥaḍara muʿallimu al-faṣli: muʿallimu is a nominative subject and the construct head; al-faṣli is genitive because it is the construct complement.
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The Head of an Iḍāfah
Choosing the Correct Parsing: Meaning, Governance and Context
Ḥaḍara muʿallimu al-faṣli: muʿallimu is a nominative subject and the construct head; al-faṣli is genitive because it is the construct complement.