युष्मद्युपपदे समानाधिकरणे स्थानिन्यपि मध्यमः

Operational rule vidhi

Where a form of the word युष्मद् shows the same substance which is shown by the लकार, there the तिङन्तपद must be expressed using the मध्यमपुरुष प्रत्ययाs.

Word by word (padaccheda)

Right context युष्मदि saptamī · ekavacanaRight context saptamī · ekavacanaRight context समान- saptamī · ekavacanaRight context स्थानिनि saptamī · ekavacanaIndeclinable अपि avyayaSubstitute / term prathamā · ekavacana

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").
Indeclinable An avyaya such as च "and", वा "optionally", न "not".
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.

See the table this defines: 3.4.78 तिङ् The 18 verb endings →

Full reading

युष्मदि समान- स्थानिनि अपि

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

Commentary

When the pronoun युष्मद् 'thou' understood, and also when the same expressed, is the attendant word in the agreement with the verb, then there is the verbal termination called the middle (2nd person).
This defines the 2nd person of conjugational affixes. As त्वं पचसि thou cookest or पचसि; युवां पचथः or पचथः you two are cooking; यूयं पचथ or पचथ you cook.

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