1. There are substitute goods too, which are in competition with each other. 2. A submodular utility function is characteristic of substitute goods . 3. All bidders regard all items as pure substitute goods , so their valuations are unit demand. 4. That's a problem because companies say they can't easily substitute goods made in other countries. 5. The 1874 invention of root rubber, quickly established it as a substitute good for traditional rubber. 6. We should be substituting good fats for bad ones rather than worrying about reducing the total amount of fat. 7. In addition, consumers have shifted to substitute goods because they have less money to buy imports, " he said. 8. But the standard, 3, 500-pound Vision TSi has a tougher suspension that substitutes good handling for a really soft ride. 9. The objects have common values to all bidders but need not be identical, and may be either complement goods or substitute goods . 10. Most studies of market structure relax a little their definition of a good, allowing for more flexibility in the identification of substitute goods .