6.3.46
आन्महतः समानाधिकरणजातीययोः
Operational rule vidhi
For the final महत् of is substituted आत् (आ) before a word which is in apposition with it and before जातीय.
Word by word (padaccheda)
Substitute / term आत् prathamā · ekavacanaTarget महतः ṣaṣṭhī · ekavacanaRight context समानाधिकरण- जातीययोः saptamī · dvivacana
- 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).
- Right context Saptamī (7th case): "when X follows", the operation applies to what precedes (1.1.66 तस्मिन्निति निर्दिष्टे पूर्वस्य). Also a condition or domain ("in the sense of").
Full reading
आत् महतः समानाधिकरण-
Pāṇini leaves out words that carry over from earlier sūtras. Expand to see the rule as a reader actually understands it.
महतः → आत् / समानाधिकरण-
Replace mahataḥ with āt when samānādhikaraṇa-jātīyayoḥ follows. Inherited words (anuvṛtti) may add further conditions.
Commentary
For the final महत् of is substituted आत् (आ) before a word which is in apposition with it and before जातीय।
As महादेवः, महाब्राह्मणः, महाबाहुः, महाबलः, महाजातीयः ॥ But महतः पुत्रः = महत्पुत्रः "the son of the great man": the two words are not in apposition. The compounding with महत् takes place under 2.1.61. This rule applies to compounds under that rule, as well as to Bahuvrihis, when also the two words are in apposition, as in महाबाहुः ॥ In fact this is the object of using the word samanadhikarana in this sutra. Had it not been used, then by the maxim of pratipadokta, the rule would have applied only to the Tatpurusha compounds of mahat taught under 2.1.61 but not to Bahuvrihis. In महद्भूतश्चन्द्रमा = अमहान् महान् संपन्नः, the long आ is not substituted, as the sense of महत् is here secondary.
Vart:- आ is substituted for the final of महत् before घास, कर and विशिष्ट, the feminine महती being changed to masculine, though the words may not be in apposition. As महत्या घासः = महाघासः, महत्याः करः = महाकरः, महत्याविशिष्टः = महाविशिष्टः ॥
Vart:- आ is substituted for the final of अष्टन् before कपाल, when a sacrificial offering is meant. As अष्टाकपालं चरुं निर्वपेत ॥ Why do we say when meaning a sacrificial offering? Observe अष्टकपालं ब्राह्मणस्य ॥
Vart:- आ is substituted for the final of अष्टन् before गौ, when the meaning is that of 'yoked'. As, अष्टागवेन शकटेन ॥ But अष्टगवं ब्राह्मणस्य, where 'yoking' is not meant. The त् in आत् is for the sake of distinctness.
Śrīśa Chandra Vasu, The Ashtadhyayi of Panini (1897), via ashtadhyayi.com.