>> "gasda" could equally well be "swiftest" I think, which
>> gives a more complete parallel with line (a).
> Absolutely. I resisted this translation myself only because I
> mechanically (and therefore foolishly) employed the rule of thumb that
> the superlative form normally invloves palatalisation of the final
> consonant (GOI §369). But looking now at the list of exceptions given
> there I note that 'assae' gives 'assu' and that DIL itself gives the
> comparative of gasta as gastu. Does 'gasda' resist/lose the
> palatalisation for similar reasons to 'assae'? Can anyone walk me
> through that?
I don't know why we have "ard > ardu" instead of "airdiu" in OI.
The odd thing is that the general rule is observed in the modern
language: "ard > níos airde". OI also has "tromm > trummu", while
today it's "trom > níos troime". I bet David can explain this.
The distinction between unstressed -u and -a gets reduced to schwa
early on, of course, so later "gasta" instead of "gastu" is normal.