In mathematics, a Hausdorff space X is called a fixed-point space if every continuous function ${\displaystyle f:X\rightarrow X}$ has a fixed point.

For example, any closed interval [a,b] in ${\displaystyle \mathbb {R} }$ is a fixed point space, and it can be proved from the intermediate value property of real continuous function. The open interval (a, b), however, is not a fixed point space. To see it, consider the function ${\displaystyle f(x)=a+{\frac {1}{b-a))\cdot (x-a)^{2))$, for example.

Any linearly ordered space that is connected and has a top and a bottom element is a fixed point space.

Note that, in the definition, we could easily have disposed of the condition that the space is Hausdorff.