Bedouin Arabic multiple opacity with indexed constraints in Parallel OT

Opaque interactions between phonological processes (Kiparsky 1973) can be a significant challenge to Optimality Theoretical accounts of phonology (Idsardi 2000, Bakovic 2011). McCarthy (2007) presents the case of multiple opacity in Bedouin Arabic that seems to require extrinsic process ordering (as provided by OT-CC, McCarthy 2007, and Serial Markedness Reduction, Jarosz 2014). It is a counterexample to the Stratal OT approach: one of the opaque processes in the interaction applies across words, which implies that it applies at the phrase level, and should be transparent according to Stratal OT. At the same time, McCarthy points out multiple opacity as a challenge to non-derivational approaches like Turbidity Theory (Goldrick 2001) or Coloured Containment (van Oostendorp 2008).I offer an account of this complex interaction in terms of a modified version of indexed constraint theory (Pater 2000): constraints are indexed to binary non-phonetic features on individual segments (Nazarov 2019, see also Becker 2009 and Round 2017). This account is compatible with Parallel OT and requires no extrinsic ordering between processes: the processes interact opaquely because of indexation. A restrictive (Richness-of-the-Base-proof) account of the opaque interaction is achieved by restricting how segments with particular indices may be realized