We investigate a monetary model in which the centralized market opens once, but the decentralized markets open twice in each period. We show that there may be multiple stationary equilibria.

We study a monetary model in which buyers choose search intensity and prices are considered as given in a decentralized market. We indicate that the Friedman rule may not be optimal.

We study the neoclassical growth model with non-constant discounting. We do not assume specific functional forms for discounting and demonstrate that the competitive economy always performs better than the planning economy.

Bliss [Bliss, C., 2008. Multiple equilibrium in the Diamond capital model. Economics Letters 100, 143–145] finds numerically that the Diamond OLG model can have uncountably many steady states. We use log preferences and show analytically that a continuum of steady states can still exist.

I correct Propositions 1, 2, 3 and 4 in Lioui and Rangvid [Economics letters 96(2007)]. Their conclusion that money demand is not well-defined for plausible parameter values under the ratio specification of habit is wrong.