Given the key assumption of Trace Theory that a moved constituent leaves behind a coindexed trace, we might formulate the relevant principle that transformations cannot downgrade constituents in terms of an equivalent condition that a moved constituent cannot occupy a lower position than any of its traces. This principle might be stated more formally as in (85) below (85) C-COMMAND CONDITION (85) A moved constituent must c-command ( = constituent-command) (85) each of its traces at S-structure (X c-commands Y just in case the (85) first branching node dominating X dominates Y, and neither X (85) nor Y dominates the other)
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