शरोऽचि

Operational rule vidhi

A शर्-letter does not undergo द्वित्वम् when followed by an अच् letter.

Word by word (padaccheda)

Target ṣaṣṭhī · ekavacanaRight context saptamī · ekavacana

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").

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

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

Commentary

There are not two in the room of a sibilant (शर्), when a vowel follows.
The word न is to be read into the sutra. This debars the application of rule 46 ante. Thus कर्षति, वर्षति, आकर्षः, अक्षदर्शः ॥

Why do we say अचि 'when a vowel follows'? Observe दर्श्श्यते ॥

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