Economists love to talk about "cross-elasticities". In English, if the price of Toyota vehicles sharply increase, how much does demand for Mercedes increase by? That's a cross-elasticity. The NY Times today has a piece about rich international real estate buyers. We all know that London and New York City and Los Angeles compete for the "high rollers". This piece argues that NYC's high end apartment owners and Don Trump (sellers of high end apartments) could be the big winner from London raising taxes on real estate.