TY - JOUR AU - Bale, Alan AU - Reiss, Charles AU - Ta-Chun Shen, David PY - 2019/12/30 Y2 - 2024/03/28 TI - Sets, rules and natural classes: [ ] vs. { } JF - Loquens JA - loquens VL - 6 IS - 2 SE - Articles DO - 10.3989/loquens.2019.065 UR - https://loquens.revistas.csic.es/index.php/loquens/article/view/73 SP - e065 AB - <p>We discuss a set-theoretic treatment of segments as sets of valued features and of natural classes as intensionally defined sets of sets of valued features. In this system, the empty set { } corresponds to a completely underspecified segment, and the natural class [ ] corresponds to the set of all segments, making a feature ± Segment unnecessary. We use unification, a partial operation on sets, to implement feature-filling processes, and we combine unification with set subtraction to implement feature-changing processes. We show how unification creates the illusion of targeting only underspecified segments, and we explore the possibility that only unification rules whose structural changes involve a single feature are UG-compatible. We show that no such Singleton Set Restriction can work with rules based on set subtraction. The system is illustrated using toy vowel harmony systems and a treatment of compensatory lengthening as total assimilation.</p> ER -