Ṭāliba is the accusative vocative and the first member of the iḍāfa; al-ʿilmi is genitive as the second member.
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Vocative in an Iḍāfa
Vocative Particles: Five Forms, Uses and Parsing
Ṭāliba is the accusative vocative and the first member of the iḍāfa; al-ʿilmi is genitive as the second member.