Proof That the Identity Function On the Unit Disc is Homotopic to the Constant Function Mapping the Disk to the Origin
That the identity function on the unit disk is homotopic to the constant function mapping the disk to (0,0).
Supposeandare unit disks andis the identity functionfor
Letbe the constant function on the unit diskfor
Letbe a point in the disk.
Letbe point on the line fromtothat is t times the distance fromto
The condition for a homotopy is met and the theorem is proved.