Chapter 9.3, Problem 29PS

To determine

To group:

The letters of the alphabet shown into classes so that all the elements within each class are topologically equivalent and no elements from different classes are topologically equivalent.

$\begin{array}{ccccccccccccc}\text{A}& \text{B}& \text{C}& \text{D}& \text{E}& \text{F}& \text{G}& \text{H}& \text{I}& \text{J}& \text{K}& \text{L}& \text{M}\\ \text{N}& \text{O}& \text{P}& \text{Q}& \text{R}& \text{S}& \text{T}& \text{U}& \text{V}& \text{W}& \text{X}& \text{Y}& \text{Z}\end{array}$