Metrically conditioned /a/-syncope in Modern Hebrew compounds

In Modern Hebrew, some, but not all, nominals exhibit obligatory /a/-syncope in open syllables if they are antepretonic in a simple (nominal) word. The same vowels optionally syncopate in any pretonic syllable in non-final members of compounds. Here we first show that syncope in compounds fills a gap in the typology of weak positions. We then propose a formal analysis in Gradient Harmonic Grammar (Smolensky and Goldrick 2016), which distinguishes between a weak /a/ and a strong /a/. Only the former undergoes syncope in both configurations; and only in non-compounds is it protected by a positional faithfulness constraint referencing the head foot of the prosodic word. Optionality in compounds is shown to follow from Base-Derivative faithfulness.