Cancellation of 3-Point Topological Spaces

[EN] The cancellation problem, which goes back to S. Ulam, is formulated as follows:

Given topological spaces X, Y, Z, under what circumstances does X × Z ≈Y × Z (≈ meaning homeomorphic to) imply X ≈ Y ?

In it is proved that, for T0 topological spaces and denoting by S the Sierpinski space, if X × S≈Y × S then X≈Y.

This note concerns all nine (up to homeomorphism) 3-point spaces, which are given in.