Pāṇini sūtras

rī is substituted for the final short ṛ of a stem, before an affix beginning with ya, when it is not a Kṛit nor a Sârvadhâtuka affix, and before the adverbial affix cvi

1. rīṅरीङ्

   Part	Lexeme	Sandhi form	Meaning	Stem
   rर्	rīṅरीङ्	rīṅरीङ्	rīṅरीङ्	rīṅरीङ्

2. ṛ+taḥऋ+तः

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   ṛऋ	ṛऋ	ṛऋ	ṛkāraऋकार	ṛऋ
   tत्	tत्	taḥतः	TT	tत् + plus aḥअः

Anuvṛtti

1. yiयि 7·4·22

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   yय्	yय्	yiयि	yakāraयकार	yय् + plus iइ

2. cvauच्वौ 7·4·26

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   cच्	cviच्वि	cvauच्वौ	cviच्वि	cvच्व् + plus auऔ

3. a+kṛt+sārvadhātukayoḥअ+कृत्+सार्वधातुकयोः 7·4·25

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   aअ	aअ	aअ	not	aअ
   kक्	kṛtकृत्	kṛtकृत्	kṛtकृत्	kṛtकृत्
   sस्	sārvadhātuसार्वधातु	sārvadhātukayoḥसार्वधातुकयोः	sārvadhātukaसार्वधातुक	sārvadhātukसार्वधातुक् + plus ayoḥअयोः