From the introduction: "The hallmark of generative phonology has been the postulation of unique underlying representations for morphemes and the derivation of surface allomorphs by means of a set of rules. In order for these rules to have the greatest generality possible, a number of linguists have proposed solutions involving underlying segments that never reach the surface with the same feature specifications that they had at the underlying level. These 'abstract' solutions have generally posited segments whose features are fully specified. [...]
"Abstract solutions have generated an abundance of discussion and some alternative proposals have been presented for most of the above analyses. Arguments have also been given to the effect that solutions with absolute neutralization are simply incorrect and that alternative concrete, morphological solutions are always preferable. In this paper I will present a case for positing an abstract segment in Seri, a Hokan language of northwestern Mexico. I will show that the motivation for this analysis is multiple and that such a solution is preferable to a concrete analysis. The abstract solution will be shown to be theoretically significant because the identity of the segment cannot be determined from the synchronic evidence; it is a truly abstract solution.
"In section 2.1-2 I will first introduce the type of allomorphy that typically occurs with the prefixes that indicate tense. In section 2.3 a class of verbs which are superficially very aberrant will be examined, and a rule feature analysis will be developed. An abstract analysis will be proposed in section 2.4. Various other alternations will be examined in section 3 and the two solutions will be simultaneously developed. Finally I will compare the solutions and discuss the consequences of adopting the abstract analysis."
Marlett, Stephen A.
"The abstract consonant in Seri,"
Work Papers of the Summer Institute of Linguistics, University of North Dakota Session: Vol. 23, Article 4.
Available at: https://commons.und.edu/sil-work-papers/vol23/iss1/4