本篇論文的主旨在於討論漢語方言中，成都話的連讀變調現象。
深究的重點是成都話連讀變調現象的變調方向性及變調方向性背後之
意義。成都話三字組的變調方向性有由右而左和由左而右兩種；其變
調方向性完全不受構詞句法結構的影響。不過，在四字組時，成都話
的變調方向卻又轉而受到構詞句法結構左右。本文根據優選理論分析
後認為，成都話三字組的變調方向性基本上是由右而左。因為這個方
向性可以使得輸出聲調和其參考的聲調（base）比較相同。當這個方
向性會衍生出高度有標（highly marked）的形式時，連讀變調規則就
會轉而由左而右運作。變調的方向性可以由音韻制約（markedness
constraint）和輸出－輸出信實制約（OO-faithfulness constraint）之間
的排列順序而得到預測。而在四字組方面，我們認為成都話四字組的
變調之所以轉而受到構詞句法結構的影響是因為，成都話限制其聲調
範疇不得大於三個音節之故。當輸入聲調大於三音節時，輸入的聲調
會拆成較小的範疇。在將聲調拆成較小的範疇時並非武斷的，而是根
據構詞句法結構。

This paper examines tone sandhi in Chengdu, which is a southwestern Mandarin
dialect spoken in Sichuan Province, China. The investigation of the tone sandhi
phenomena reveals some rather interesting properties of Chengdu. First, in tri-tonal
strings, both left-to-right and right-to-left tone sandhi operation directionalities are
observed; nonetheless, the operation directionalities appear to be ungoverned. Second,
in quadri-tonal strings, morphosyntactic structures, which are completely functionless
in predicting tone sandhi in tri-tonal strings, start to be respected. In this paper, I
argue that the tone sandhi operation directionality in tri-tonal sandhi is by no means
ungoverned. Normally tone sandhi operates from right to left for identity reasons,
unless marked forms would be generated. In that case, tone sandhi operates reversely
from left to right. Thus, the seemingly unpredictable tonal operation directionality in
tri-tonal strings is naturally captured by the interaction of the identity and the
markedness constraints. As for why morphosyntactic structure starts to take a role in
quadri-tonal sandhi, I argue that Chengdu has an upper limit on the size of the tone
sandhi domain, which is three syllables. When the strings exceed the upper limit of
the domain size, they are divided into independent domains to avoid generating
oversized ones. The division of the strings into different domains is not ad hoc, but is
sensitive to morphosyntactic structures.