> Question: initial /a/ and /o/ in PIE daughter-languages (i.e., Latin
> and Greek) are always caused by initial laryngeals in the parent
> language, correct?
No. In Greek some initial /a/ < *h2, but analogy and a kind of vowel
harmony mess things up. Initial /a/ can also come from other sources,
e.g. syllabic n (think of the a- prefix in a-theist, a-moral etc)
In Latin an initial laryngeal normally disappeared (nomen, Greek onoma) ,
but initial *he could survive (emo, aqua, olo). Latin /a/ in the first
syllable has a number of origins, not all well understood.
Peter