After a consonant, the following semi-vowel or a nasal is elided optionally, when the same letters follow it,
The word अन्यतरस्याम् should be read into the sutra. Thus शय्य्या or शय्या, the middle य् being elided. In शय्या there are two यs, one of the affix क्यप् 3.3.99; and the second of अयङ् 7.4.22, and the third arises by doubling 8.4.47. आदित्य्य (formed by doubling य by the Vartika under 47 ante), or आदित्य 'son of Aditi' In आदित्य्य there are two यs, one of ण्य 4.1.85, and the second arises by doubling.
Similarly आदित्य देवता अस्य स्थाली पाकस्य = आदित्य्य ॥ Then by 8.4.47, there is a third य, as अदित्य्य ॥ Here also we may elide the one middle य or both the middle य's. Thus आदित्यः or आदित्य्य ॥
Why do we say हलः 'preceded by a consonant'? Observe अन्नम् when म् is preceded by a vowel.
Why do we say यमाम् \of यम् letters\? Observe अग्ग्निः, अर्घ्यम् 5.4.25 where घ is not a य ॥
Why do we say यमिं \when यम् follows\ ? Observe शार्ङ्गम् here ङ् is not followed by a यम् ॥,