When Can Manipulations be Avoided in Two-Sided Matching Markets? -- Maximal Domain Results

In two-sided matching markets, stable mechanisms are vulnerable to various kinds of manipulations. This paper investigates conditions for the student-optimal stable mechanism (SOSM) and the college-optimal stable mechanism (COSM) to be immune to manipulations via capacities and pre-arranged matches. For SOSM, we find that strongly monotone preferences in populations and weakly maximin preferences are the maximal domains of college preferences that guarantee immunity to manipulations via capacities and pre-arranged matches, respectively. In contrast, COSM is susceptible to both manipulations whenever colleges have multiple positions.