Logical approaches to linguistic description, particularly those which employ feature structures, have generally treated phonology as though it was the same as orthography. This approach breaks down for languages where the phonological shape of a morpheme can be heavily dependent on the phonological shape of another, as is the case in Arabic. In this paper we show how the tense logical approach investigated by Blackburn (1989) can be used to encode hierarchical and temporal phonological information of the kind explored by Bird (1990). .
