In mathematics, the set is (a collection of objects that have clearly defined properties) all collections of certain objects that are considered as one entity. Although this is a simple idea, it is not wrong if the set is one of the essential and fundamental concepts in modern mathematics, and hence, the study of the structure of possible sets and set theory is very useful.
The slices of the two sets are expressed with Venn diagrams
The set theory, newly invented in the late nineteenth century, is now a scattered part of mathematical education that has begun to be introduced even from the elementary school level. This theory is the language to explain modern mathematics. Set theory can be considered as a foundation that builds almost all aspects of mathematics and is the source from which all math is derived.
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Typically, the set name is written in capital letters, such as S, A, or B, while the set members are written in lowercase (a, c, z). This method of writing is commonly used, but it is not limiting that each set should be written in such a way. The table below shows the commonly used set of writing formats.