BOSHAN TONE SANDHI
This paper investigates the tone sandhi phenomenon in Boshan, which is remarkable for its seemly unpredictable rule application directionalities observed in tri-tonal strings. Based on the constraint-based theory of OT, this paper shows that the rule application directionalities in Boshan are by no means ungoverned. Normally tone sandhi applies from left to right for identity reasons, unless highly marked forms would be generated. In that case, tone sandhi applies reverselyfrom right to left. Thus, the rule application directionalities are naturally predicted by the interaction of the identity and markedness constraints. The investigation of the issue of directionality in Boshan also supports the view that identity preservation between prosodically related outputs is important in tone sandhi. The output-to-output correspondence relation may force a tonal output to deviate from the canonical surface patterns of the language, so that it becomes more like a tonal base to which it prosodically relates. Identity preservation is highly respected in tone sandhi, unless this would produce forms that are highly marked.