(The y when preceded by 1. bho 2. bhago 3. agho 4. a or 5. ā , is elided) before a consonant according to the opinion of all ācārracā-s.,
Thus भो हसति, भगो हसति, अघो हसति; भो याति, भगो याति अघो याति, वृक्षा हसन्ति ॥ Though the anuvritti of व् and य् both is present here, yet we have taken य only to the exclusion of व् ॥ Because भो, भगो and अघो there is य् only, and never व्; and व् can come only when preceded by अ or आ : the only example of which given by Grammarians is वृक्षव् करोति 8.3.17. Here व् is not elided, because the word अशि qualifies the word हलि of this sutra.
Question:- But व् should be elided in वृक्षव् हसति, because ह is an अश् letter.
Answer:- There is no such example to be found in any standard author. Moreover Patanjali in his commentary on the Pratyahara sutra लण् says that no words can end in ह्, य्, र्, व् or ल् ॥ So that the existence of the very word वृक्षव् is doubtful.
The word sarvesham indicates that 8.3.18, even does not apply, and there is no light articulation, but lopa there too.,