इको ऽचि विभक्तौ

Karika-
इकोचि व्यञ्जने मा भूदस्तु लोपः स्वरः कथम् ।
स्वरो वै श्रूयमाणो पि लुप्ते किं न भविष्यति ॥
रायात्वं तिसृभावश्च व्यवधानान्नुमा अपि ।
नुड् वाच्य उत्तरार्थे तु इह किं चित्रपो इति ॥

Thus त्रपुणी, जतुनी, तुम्बुरुणी, त्रपुणे, जतुने, तुम्बुरुणे ॥ Why \with the exception of अ\? Observe कुण्डे, पीठे ॥ The phrase \before an affix beginning with a vowel\ is employed here for the sake of the subsequent sutras like 7.1.75. Here we could have dispensed with it: for before affixes beginning with a consonant नुम्, would be elided by 8.2.7. The only object that it serves here is that we can form हे त्रपो ! or हे त्रपु ! in the Vocative singular. For had we त्रपुन् + स् in the vocative, the form would have been हे त्रपुन् like हे राजन्, for न् would not be elided here, see 8.2.8.

If it be objected that by the sutra न लुमताङ्गस्य 1.1.63 when the affix स् is elided in the Vocative, it will leave no trace behind, and there being no affix at all, नुम् will not be added in the Vocative. We reply: that this very employment of the word अच् in this sutra indicates (jnapaka) that the rule prohibiting the effect of an affix 1.1.63 does not apply here. Therefore, though the affix is elided, it produces its effect in spite of 1.1.63, and we have the guna of the vowel in the Vocative, as हे त्रपो by 7.3.108.

Why have we used the word विभक्तौ 'when a case-affix follows'? Observe तुम्बुरवं चूर्णम्, where the Taddhita affix अञ् is added to तुम्बुरु by 4.3.139.

Karika: - The employment of the words इकः अचि in the sutra shows that नुम् will not come when the affix begins with a consonant, as त्रपुभ्यां, त्रपुभिः ॥ An objector says, the employment of अचि in the sutra is useless for नुम् may be added even before an affix beginning with a consonant, for having added it, it will be elided by न लोपः प्रातिपदिकान्तस्य 8.2.7. We reply, yes it can be so done, but how will you then manage the accent? For in पञ्चत्रपुभ्यां, पञ्चत्रपुभिः, the accent is regulated by the rule 6.2.29 which says that in a Dvigu compound, the first member preserves its original accent if the second member ends in an इक् vowel. But if there was a नुम्, then the second member would not end in इक् but in न् : and the elision of this न् by 7.2.7 is asiddha for the purposes of accent. To this the objector answers, that even where न् is not elided the accent is governed by 6.2.29, namely the accent of पञ्चत्रपुणे or पञ्चत्रपुण : is by 6.2.29, why should it not be so when न् is elided. So the objection about accent has no strength.

Well if नुम् be added even before consonant-affix, then there will arise this anomaly: अतिरि + भ्यां = अतिरिन् + भ्यां (by adding नुम्). Here rule 7.2.85 cannot apply: because न् intervenes between रि and भ्यां, therefore इ of रि is not changed to आ, and therefore we cannot get the proper from अतिराभ्यां ॥ Moreover in प्रियत्रि + भ्यां, the त्रि cannot be changed to तिसृ if there be नुम्, and so we cannot get the form प्रियतिसृभ्यां ब्राह्मणकुलानि ॥

To this it is answered, the change of इ into आ in the case of रि, and the substitution of तिसृ for त्रि will take place even when the नुम् intervenes, on the maxim विभक्तिविधानदशायां यदानन्तर्ये तत् तत्राश्रीयते न त्वादेशविधानदशायाम् ॥ And this is done in this way : अतिरि + भ्यां, and प्रियत्रि + भ्यां, here नुम् is superseded by the subsequent rule requiring आ and तिसृ respectively.

If this be so, then the employment of अच् in the sutra is for the sake of the supersession of नुम् by नुट् 7.1.54. Thus नुट् has unrestricted scope in अग्नीनां, वायूनां, and नुम् has unrestricted scope in त्रपुणे and जतुने ॥ But in त्रपूणाम् and जतूनाम्, both नुट् and नुम् present themselves. Here however नुम् is superseded by नुट् by purva-vipratishedha and so there is lengthening of the vowel by 6.4.3. This supersession is indicated by the employment of अच्, for नुट् and नुम् being both anitya and of equal force, had there been no अच्, नुम् would have come and not नुट् ॥

But this is also not valid, for नुट् would have to be added, even if there had been no अच् in the sutra.

The employment of अच् is for the sake of the subsequent sutra 7.1.75. The only object that अच् serves in this sutra, is in forming the vocative हे त्रपो as shown above.,