6 - Grid Well-formedness: Clash and Lap

Summary

There are two general well-formedness principles that shape the metrical grid: clash avoidance and lapse avoidance. Clash is a configuration on the metrical grid where two entries on one level do not have an intervening entry on the next level higher. Clash avoidance plays a key role in restricting the range of binary default systems predicted under a Weak Bracketing approach. It prefers patterns where overlapping feet share grid entries rather than mapping to separate entries. Clash avoidance is also plays a key role in producing rhythm rule effects, where prosodic word-level and phonological phrase-level prominences shift to create a more regular, even distribution. A lapse is a configuration where two adjacent entries on one level both fail to support an entry on the next level higher. Lapse avoidance plays a key role in creating the fine-grained prominence distinctions on the metrical grid that cannot be accounted for with MAP constraints. Finally, extended lapse is a configuration where three adjacent entries on one level all fail to support an entry on the next level higher. Extended lapse avoidance is the key factor in producing the few ternary patterns found among the world’s languages.