Conjunto De Operaciones (Bajado De Internet)

Sets: Properties and Operations
What is a Set? A set is a collection of discrete data items. The members of the set can be numbers or names. Describing a Set There are two distinct ways ofdescribing the members of a set. One is to list them explicitly, like you would find in a database of names. A = { Mark, Angela, Frank, Laura } A couple features of sets is that order doesn’t matter, andduplicates don’t really count. { Mark, Angela, Frank, Laura } = { Laura, Frank, Mark, Angela } and { Mark, Angela, Frank, Laura } = { Mark, Laura, Angela, Mark, Frank, Laura } One way to think of this is adatabase query using the “unique” keyword. Similarly, order is a matter of how we want the set contents listed. A class list can be ordered by student name, or student number, depending on what it isused for. We commonly remove duplicates for convenience, although they are occasionally used depending on the specific application. Another way to define a set is to describe a mathematicalrelationship. A = {x | 2x + 6 = 0 } The vertical bar can be read as “such that”, so that the entire statement would be read as “set A consists of members solving for x, such that 2 times x plus 6 equals 0”This same set can be listed explicitly. A = { -3 } Variables used to identify sets are usually denoted with uppercase letters, such as A. Lowercase letters usually refer to specific member of a set bythe uppercase name. Thus, a is the variable we would use to refer to a member of set A. We can write this like this: a∈A
Discrete/Computer-Based Math CIS 125 5-1

This can read as “a is a member ofset A”, or “a is an element in set A”. The symbol for the member can be any variable. x∈A (member / element of)

Similarly, we use a slightly different symbol to state that the content of a variableis not a member of a particular set. x∉A (not a member / element of)

This notation is good for individual members, but what if we are trying to compare a group of set members? For that we have...