Re: [tied] n/r (was: PIE suffix *-ro - 'similar-with')

> Patrick:
> there is _no_ nasal infix. There is a nasal suffix which, under certain
> conditions, undergoes metathesis.

That may depend on the time you are talking about. I think it is
incontrovertible that IE languages inherit forms with nasal infixes (e.g.
*iu-n-g-o). But I accept that in theory these could have arisen from
something else at an earlier stage.
What would you say these conditions are, under which a nasal suffix
metathesises?

Peter