A Percolative Account of Tianjin Tone Sandhi

This paper presents data from Tianjin tritonal sandhi patterns that challenge both traditional derivational approaches and standard Optimality Theoretic (OT) approaches to phonological alternation. If construed derivationally, Tianjin tritonal sandhi requires derivational reversals; but if construed within OT, involves combinations of opacity and transparency. The account proposed here appeals to a percolative model where phonological information from terminal nodes finds correspondences in higher nodes, such that the correspondences may be imperfect when triggered by markedness requirements. While this requires a total reconceptualization of phonological representations, this paper argues that it is well worth it because it predicts that: (1) directionality is a derivate from branching; (2) the depth of derivational opacity is confined by structural depth; (3) constituency, not adjacency, provides the environment for triggering alternation so alternation rules can therefore be blocked when marked collocations belong to different constituencies; and (4) underlying entities can have split surface correspondences.