We propose that signalling in professional labour markets creates product market externalities that affect wages, thus establishing a link between the externality and signalling incentives. Due to signalling activity, a free substitute (negative externality) or complement (positive externality)...

The future compatibility of a product can be important to a buyer. With IT products, switching costs may in the worst case well exceed the purchasing price. We develop a model in which rational buyers value products by their expected levels of future compatibility, using suppliers' R&D budget...

Software firms are observed to support programmers' communities, which develop rival open source programs. A firm selling a copyright program has an incentive to support substitute copyleft programming when support creates compatibility between the programs and programs exhibit network effects....