Maqṣūr: الْعَصَا — the final alif cannot bear a case vowel; the cause is impossibility.
Noun with possessive yāʾ: غُلَامِي — the preceding mīm must keep the kasra needed before yāʾ; the position is already occupied by that vowel.
Both take estimated endings in all three cases, but the underlying reason differs.
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Noun Case Class 7 — Maqṣūr and Nouns with Possessive Yāʾ
Maqṣūr: الْعَصَا — the final alif cannot bear a case vowel; the cause is impossibility.
Noun with possessive yāʾ: غُلَامِي — the preceding mīm must keep the kasra needed before yāʾ; the position is already occupied by that vowel.
Both take estimated endings in all three cases, but the underlying reason differs.