We present a theory for why it might be rational for a platform to limit the number of applications available on it. Our model is based on the observation that even if users prefer application variety, applications often also exhibit direct network effects. When there are direct network effects,...

We show that all the fundamental properties of competitive equilibrium in Marshall's cardinal theory of value, as presented in Note XXI of the mathematical appendix to his Principles of Economics (1890), derive from the Strong Law of Demand. That is, existence, uniqueness, optimality, and global...

Neoclassical tools of marginalism and profit maximization are used to measure labor's surplus value. Recent empirical estimates of a firm's wage elasticity of labor supply imply a surplus so large that the value of labor may exceed the total value of a firm's production. Labor value in excess of...