We propose a formal description of individual preferences that captures a subsistence requirement in consumption in an otherwise standard constant-elasticity-ofsubstitution (CES) utility specification. We study how substitutability between the subsistence good and another good depends on the...

This paper provides a new test for whether different-currency assets are imperfect substitutes. The test exploits that under floating rates, changing public currency demand has no direct effect on monetary fundamentals, current or future. Price effects from imperfect substitutability are clearly...