How to write phonology rules using features?

Question

Is there a way to write the following phonology rule using features?

The /u/ becomes [ɯ] word-finally when preceded with an unrounded vowel with 1 or more intervening consonants. .

Answer 1

The standard statement of that rule would be:

[+syllabic,+hi,+round] → [–syllabic]/ [+syllabic,–round] [-syllabic]₁__ #

There are other imaginable expressions that have the same effect, depending on (1) what other vowels there are in the language and (2) what you mean by "consonant". Also, this is in SPE theory, whereas when you get into autosegmental rule statements, there is no standard.

Or, if you want the result to be a back unrounded vowel [ɯ], modify the above to

...→ [–round]...

You could also state the rule as

[+syllabic,+hi,+round] → [αround]/ [+syllabic,αround] [-syllabic]₁__ #

which achieves the same thing, insofar as it does not change anything after a [+round] vowel.