In their paper, “Economic Models for R&D Project Selection in the Presence of Project Interactions,” Fox, Baker, and Bryant (Fox, G. E., N. R. Baker, J. L. Bryant. 1984. Economic models for R and D project selection in the presence of project interactions. Management Sci. 30 (July) 890–902.) proposed a model that included benefit interactions, called present value (PV) interactions, between R&D projects. Several computational errors in this paper invalidated the illustrative example which sought to demonstrate that ignoring the PV interactions could result in both nonoptimal project selections and resource allocations. However, a single correction yields an example that supports the authors' central premise. Furthermore, we believe that the model itself can prove useful in real applications.

In the paper by Graves and Schwarz [Graves, Stephen C., Leroy B. Schwarz. 1977. Single cycle continuous review policies for arborescent production/inventory systems. Management Sci. 23 (5, January) 529–540.], we observed an error in their discussion of optimal policies for the one warehouse-m retailer system. Specifically, Theorem 1, which states that the optimal stationary policy is a single-cycle policy, is incorrect.