JS Bangs wrote:
> The general sonority goes obstruents, nasals, liquids, approximants,
> vowels. Minimum sonority distance is 1.
> Russian /v/ acts like it was /w/--i.e. it is more sonorouss than /r/ or
> /l/. Thus the sonority distance between the initial consonants of /tvoj/
> "yours" is 3, not 0.
> You can add one extra segment to the beginning of a word that violates
> sonority.  You can also add /s/ to the beginning of any sequence that
> doesn't violate sonority (but not to the beginning of a sequence that
> *does* violate sonority--see below).
> I think this covers it.

You probably need to add "z" to the "s"-class, to account for words
starting with <vz-> (<vzdox>, <vzdrognut'>), as well as <mzda>.

But even then, your rules won't cover the cases when single-consonant
prepositions <k>, <v>, <s> do not get the epenthetic vowel:

<k vstreche> /kfstre-/, <v l'vinyj> /vl'vi-/, <s mneniem> /smne-/

which they don't half the time.


PS. On a side note - my favourite poet, Marina Tsvetayeva, once
wrote a line:

        ... tak k komu zhe ...

with a footnote about the triple "k" reflecting her disoriented state
of mind at the time of writing.