Manipulability and Tie-Breaking in Constrained School Choice

Abstract

In constrained school choice mechanisms, students can only rank a subset of the schools they could potentially access. We characterize dominant and undominated strategies in the constrained Boston (BOS) and deferred acceptance (DA) mechanisms. Using our characterization of dominant strategies we show that in constrained DA, the single tie-breaking rule outperforms the multiple tie-breaking rule in terms of both manipulability and stability. We also show that DA is less manipulable than constrained BOS in the sense of Arribillaga and Masso (2015). Using our characterizations of undominated strategies, we derive advice for the students and show that more strategies can be excluded on the basis of dominance in constrained DA than in constrained BOS.