लोपः शाकल्यस्य

Operational rule vidhi

According to Shakalya, a वकार/यकार present at end of a पद and situated after अ/आ gets removed when it is followed by a letter from अश् प्रत्याहार in the context of संहिता.

Word by word (padaccheda)

Substitute / term prathamā · ekavacanaTarget शाकल्यस्य ṣaṣṭhī · ekavacana

Substitute / term Prathamā (1st case): in operational rules, the substitute or the thing introduced; in definitions, the term or its referent.
Target Ṣaṣṭhī (6th case): names what gets replaced, "in place of X" (1.1.49 षष्ठी स्थानेयोगा).

Dotted words are technical terms, dashed ones pratyāhāras (names for classes of sounds or affixes). Hover or tap one to see its card.

Full reading

शाकल्यस्य

Pāṇini leaves out words that carry over from earlier sūtras. Expand to see the rule as a reader actually understands it.

As a rewrite rule (sketch from case endings)

शाकल्यस्य →

Replace śākalyasya with lopaḥ. Inherited words (anuvṛtti) may add further conditions.

Commentary

व् and य् preceded by अ or आ and the end of a पद are elided before an अश् letter (vowels and soft-consonants) according the opinion of शाकल्य।
As क आस्ते or कयास्ते, काक आस्ते or काकयास्ते, अस्मा उद्धर or अस्मायुद्धर, द्वावत्र or द्वा अत्र, असावादित्यः or असा आदित्यः ॥

The name of Sakalya is used to make it an optional rule. Therefore, where there is not the lighter articulation of व् and य् by the last sutra, there also in the other alternative the fuller sounds of व् and य् are heard. Thus there are three forms, heavy व् and य्, light व् and य् and elision of व् and य् ॥

When व् and य् are preceded by ओ, then there is elision by the next sutra compulsorily.

Śrīśa Chandra Vasu, The Ashtadhyayi of Panini (1897), via ashtadhyayi.com.