ϕ : S 1 × S 1 → S 1 × S 1 {\displaystyle \phi :S^{1}\times S^{1}\rightarrow S^{1}\times S^{1}} Defined by ϕ ( θ 0 , θ 1 ) = ( 3 θ 1 , θ 1 ) {\displaystyle \phi (\theta _{0},\theta _{1})=(3\theta _{1},\theta _{1})}
Defined by 
