### Tim Hutton

Shared publicly -http://www.math.univ-toulouse.fr/~cheritat/StraightSQ/slit-1.html

The classical phenomenon it illustrates can be presented as follows:

It shows two equivalent points of view on some strange world:

left: Stickman lives in a normal world with a portal. Stickman's size is divided by 3 when it passes the portal in one direction, multiplied in the other direction.

right: Stickman lives in a world without portals and where going away and coming back leaves you with your initial size, except if you traveled around the singularity.

The correspondence between the two worlds is given by a holomorphic function: z maps to z to the power alpha, where alpha is a well-chosen complex number.