3-3 How do Porter's competitive forces model, the value chain model, synergies, core competencies, and network economics help companies develop competitive strategies using information systems? Define Porter's competitive forces model and explain how it works. Describe what the competitive forces model explains about competitive advantage. List and describe four competitive strate- gies enabled by information systems that firms can pursue. Describe how information systems can sup- port each of these competitive strategies and give examples. Explain why aligning IT with business objec- tives is essential for strategic use of systems. Define and describe the value chain model. Explain how the value chain model can be used to identify opportunities for informa- tion systems. Define the value web and show how it is related to the value chain. Explain how the value web helps busi- nesses identify opportunities for strategic information systems. Describe how the Internet has changed competitive forces and competitive advantage. Explain how information systems promote synergies and core competencies. Describe how promoting synergies and core competencies enhances competitive advantage. Explain how businesses benefit by using network economics and ecosystems. Define and describe a virtual company and the benefits of pursuing a virtual company strategy.