Example 0.4.3.

Which of the following diagrams represent a function? Let \(X = \{1,2,3,4\}\) and \(Y = \{a,b,c,d\}\text{.}\)

Picture labeled f:X to Y with two rows of numbers and letters and arrows between the rows. Top row contains the numbers 1, 2, 3, and 4. Bottom row contains letters a, b, c, and d. Arrows point from 1 to d, 2 to a, 3 to c, and 4 to d.
Picture labeled g:X to Y with two rows of numbers and letters and arrows between the rows. Top row contains the numbers 1, 2, 3, and 4. Bottom row contains letters a, b, c, and d. Arrows point from 1 to d, 2 to a, 3 to a, and 4 to b.
Picture labeled f:X to Y with two rows of numbers and letters and arrows between the rows. Top row contains the numbers 1, 2, 3, and 4. Bottom row contains letters a, b, c, and d. Arrows point from 2 to a and also 2 to c, 3 to d, and 4 to b.
Solution.
in-context