12: Cardinality
- Page ID
- 83461
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- 12.1: Finite Sets
- For m∈N we have defined the counting set N<m={n∈N|n<m}={0,1,…,m−1}.
- 12.2: Properties of finite sets and their cardinality
- Recall that a function f:N<n→A defines a finite sequence of elements from the set A, by setting a0=f(0),a1=f(1),a2=f(2),…,an−1=f(n−1).
- 12.3: Relative Sizes of Sets
- We have defined a set A to be finite when we can count its elements by matching them bijectively with the elements of some counting set N<m.
- 12.4: Counting elements of finite sets with bijections
- In a future chapter, we will begin learning how to count complicated collections by counting the “choices” needed to determine an arbitrary element in the collection.