رَأْسٌ → رَاسٌ, يَسْأَلُ → يَسَلُ, and أَأْمَنَ → آمَنَ illustrate three different processes.
The first is permitted substitution for a quiescent hamzah; the second is optional vowel transfer followed by elision; the third is obligatory substitution under a two-hamzah condition.
A correct morphological analysis names the triggering condition, not just the final spelling. Otherwise every long vowel could be mistaken for an original weak radical, and distinct types of deletion could be conflated.
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Surface Reduction and Root Identity
Rules of Hamzated Forms: Lightening, Substitution, Elision and Short Paradigms
رَأْسٌ → رَاسٌ, يَسْأَلُ → يَسَلُ, and أَأْمَنَ → آمَنَ illustrate three different processes.
The first is permitted substitution for a quiescent hamzah; the second is optional vowel transfer followed by elision; the third is obligatory substitution under a two-hamzah condition.
A correct morphological analysis names the triggering condition, not just the final spelling. Otherwise every long vowel could be mistaken for an original weak radical, and distinct types of deletion could be conflated.