Interesting, for the infinite dihedral group, I was expecting a connection between the symmetries of a circle (imagining a "polygon with infinite sides").
Consider a regular polygon with $N$ sides, for $N\geq 3$. Its group of symmetries has different notations: Group theory: $D_{2N}$. Geometry: $D_N$. Students should use their instructors' notation.
Great illustration at 15:30 !
This turtle was very funny.
Interesting, for the infinite dihedral group, I was expecting a connection between the symmetries of a circle (imagining a "polygon with infinite sides").
🐢😎
The naming is bad. D8 should be named D4.
D_2n denotes the number of elements though
Consider a regular polygon with $N$ sides, for $N\geq 3$. Its group of symmetries has different notations:
Group theory: $D_{2N}$.
Geometry: $D_N$.
Students should use their instructors' notation.