Praudhamanorama p129

p129

On "idudupadhasya cāpratyayasya" (Pā. Sū. 8.3.41): The connection is construed with different referents (vaiyadhikaraṇya): "the visarjanīya which is a part of that aggregate whose penultimate sounds are i or u". But "apratyayasya" is construed as: "the visarga which is not an affix". For when coreference (sāmānādhikaraṇya) is possible, non-coreference is improper. And it should not be said that being an affix is not known in the case of a visarga, because it is well known through treatment like the original (sthānivadbhāva) in cases like agniḥ karoti. Nor should it be suspected that the Tripādī is not established with respect to extended application (atideśa), because validity is indicated precisely by the prohibition "apratyayasya". For this very reason the visarga of ru is established in cases like agniḥ; otherwise, because it is not pada-final, it would not occur, whereas the rule enjoining visarga is fulfilled in cases like punar. And an indicator depends on a specific requirement; therefore, "acaḥ parasmin—" (Pā. Sū. 1.1.57) does not apply in the Tripādī. And thus the conclusion that "there is no treatment like the original with respect to what is not established in the preceding [portion]" is rooted in the stated reasoning and is not based on an explicit precept; this has been expounded in detail by us in the Śabdakaustubha.
If it is objected: does it not follow, in this way, that ṣa-substitution would occur in mātuḥ kāryam and the like? No; for the listing of the word bhrātuṣputra among the kaskādi group indicates that "there is no ṣa-substitution after the u-sound that comes from the a of ṅasi and ṅas". And thus, Haradatta's statement that even "apratyayasya" has different referents (vyadhikaraṇa) is not to be excessively respected.
On "mātuḥ": for here the rule of single replacement, "ṛta ut" (Pā. Sū. 6.1.111), is indirectly the cause with respect to the visarga. In the source text, however, the prevalent reading is "ekādeśaśāstranimittāt"; there, the meaning is: "after that u-sound of which the rule of single replacement is the cause".
In "muhuḥ kāma": here "kupvoḥ ka pau" (Pā. Sū. 8.3.37) applies. In the vṛtti, the reading "muhuskāma" with an s-sound is read in some places; that is an oversight, according to Haradatta.