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Chapter2Strings, Sets, and Binomial Coefficients

Much of combinatorial mathematics can be reduced to the study of strings, as they form the basis of all written human communications. Also, strings are the way humans communicate with computers, as well as the way one computer communicates with another. As we shall see, sets and binomial coefficients are topics that fall under the string umbrella. So it makes sense to begin our in-depth study of combinatorics with strings.