अस्यतेस्थुक्

Operational rule vidhi

The अङ्ग (stem) अस् 'to be' (अस्यते) gets the augment थुक् before this Aorist अङ्.

Word by word (padaccheda)

Target अस्यतेः ṣaṣṭhī · ekavacanaSubstitute / term थुक् prathamā · ekavacana

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

Dotted words are technical terms. Hover or tap one to see its card.

अस्यतेः थुक्

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)

अस्यतेः → थुक्

Replace asyateḥ with thuk. Inherited words (anuvṛtti) may add further conditions.

The अङ्ग (stem) अस् 'to be' (अस्यते) gets the augment थुक् before this Aorist अङ्।
As आस्थत्, आस्थताम्, आस्थन् ॥ See 3.1.52.

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