Can the Brouwer fixed point theorem be formulated for non-Hausdorff spaces ? More particularly, is there a formulation of the Brouwer fixed point theorem which covers both the standard case of metrizable spaces, and the case of finite topological spaces ? For example, is the following true: > Each endomorphism of a quasi-compact $T_0$ space which is an absolute extensor for normal spaces, necessarily has a fixed point. As pointed out in comments by Michael Greinecker, [Kinoshita, 1953](http://matwbn.icm.edu.pl/ksiazki/fm/fm40/fm4019.pdf) gives a counterexample to the following which is a contractible compact subset of $\Bbb R^3$, see also [Bing,The elusive fixed point property](http://www.jstor.org/stable/2317258) and references in https://mathoverflow.net/questions/59796/the-generalization-of-brouwers-fixed-point-theorem. > Each endomorphism of a contractible quasi-compact $T_0$ space necessarily has a fixed point. (false!) hence we replace "contractible" by "absolute extensor" Note that being $T_0$ is necessary: the indiscrete space with two points is quasi-compact and contractible, yet the permutation of the two points has no fixed point. Perhaps one can relax the notion of a fixed point, e.g. by requiring that $x$ and $f(x)$ are topologically indistinguishable. By the Brouwer theorem for finite topological spaces I mean what is implied by the Brouwer fixed point theorem for the geometric realisation of a finite topological space: namely, an endomorphism $f:K\to K$ of a finite topological space $K$ has a fixed point provided the endomorphism $\lvert f\rvert\colon\lvert K\rvert\to\lvert K\rvert$ of the geometric realisation of $K$ has a fixed point.