On the strategic non-complementarity of complements

This paper examines the equilibrium provision of a public good if the private monetary contributions of identical agents are (im)pure complements. To reconcile complementarity in contributions with the apparent substitutability of monetary payments, we assume a setup with multiple inputs into a complementary production function. This paper proves the uniqueness and symmetry of the equilibrium for any impure complementarity if each agent is permitted to contribute to any input in the equilibrium, contributions are strategic substitutes. Only pure complementarity exhibits multiple equilibria, where contributions are either strategic substitutes or strategic complements.