Today's class is brought to you by wallpaper patterns.
Topics
More analysis of wallpaper patterns. Why 90-degree rotations form square patterns
Class Schedule
More examples of plane symmetries.
The main idea: The composition rules and the group property force rotation centers into certain patterns. For 90-degree centers, these patterns are square of 90-degree centers with 180-degree centers in the centers of the squares. See the same Wallpaper
Patterns as last week for a good explanation.
Assignments
New
Reading Assignment
Continue reviewing Brown, especially the sections about rotations as double reflections and composition of rotations.