### Unit 5: Logic

We have already briefly discussed logic, but this unit will provide you with a more formal definition. We will learn about two main types of logic--propositional and first-order. Prolog was designed for expressing logic. This unit gives you a strong foundation in logic so that you will be able to use or learn Prolog more easily to program logic applications. Similarly, you will be able to use or learn class libraries that support AI techniques in other languages, like C++ and Java.

**Completing this unit should take you approximately 24 hours.**

### 5.2: Some Examples of Practical Applications

Read Chapters 3 through 5. Chapter 3 gives examples and tools for applying logic. Chapter 4 discusses the Semantic Web. Reasoning assumes a body of data from which inferences can be made, and this chapter discusses the Semantic Web as a source of data for use in programs, in particular for inference algorithms. Chapter 5 gives examples and tools for expert systems application in reasoning.