Finite-state Optimality Theory: non-rationality of Harmonic Serialism

This paper analyzes the language-theoretic complexity of Harmonic Serialism (HS), a derivational variant of Optimality Theory. I show that HS can generate non-rational relations using strictly local markedness constraints, proving the “result” of Hao (2017), that HS is rational under those assumptions, to be incorrect. This is possible because deletions performed in a particular order have the ability to enforce nesting dependencies over long distances. I argue that coordinated deletions form a canonical characterization of non-rational relations definable in HS.