deriv SD cv (247) ashtadhyayi.com hei.de L 247 ETT STT a 7.3.117 ALPH OLDHOMEPAGE NEWHOMEPAGE

id;udbhyAm इदुद्भ्याम् ONPANINI 73117

Replace /Gi by Am आम् after a /nadI ending in i इ u उ.

Such i इ u उ bases are /nadI only when f and only optionally, by Gitihrasvazca, so this sUtra is optional too. So if we take the option we get —

**mati- मतिॱ f + /Gi
→ (making it is /nadI by optional Gitihrasvazca)
→ mati- मतिॱ + Am आम् by this rule
→ maty- मत्य् + Am आम् by ikoyaNaci
→ !**matyAm मत्याम् "in the opinion"

**dhenu- धेनुॱ f + /Gi → !**dhenvAm धेन्वाम् "about cow"

**buddhi- बुद्धिॱ f + /Gi → !**buddhyAm बुद्ध्याम् "in the intellect"

But we don't take the option in Gitihrasvazca, then accagheH >> will replace i इ u उ with au औ —

matau मतौ "in the opinion"
dhenau धेनौ "about cow"
buddhau बुद्धौ "in the intellect"

Wawawait, something is fishy here. If this sUtra did not exist, wouldn't < GerAmnadyAmn... have taken care of short i इu उ anyway?

Yes, it would. But this was made into a separate sUtra so that aut > inherits the word id;udbhyAm इदुद्भ्याम् "short i इ u उ".