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Darboux Map


A Darboux map is a map between topological spaces that sends every connected subset to a connected subset. Every continuous map has this property. For real-valued functions on an interval, it is the intermediate value property, which can hold even for discontinuous functions.

A bijective Darboux map need not have a Darboux inverse in general. The corresponding question for a bijection R^n->R^n is more restrictive. For n=1 an injective function with the intermediate value property is strictly monotone, and its inverse has the same property.

Peter (2026) proposed counterexamples for n>=2 using recurrent tubes. The publicly released manuscript remained incomplete and the proposed construction had not received independent verification as of Sep. 7, 2026. The release disclosed a substantial AI role in developing the proposed argument.


See also

Connected Set, Continuous Function, Intermediate Value Theorem

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References

Peter, L. "Recurrent Tubes and Connectedness-Preserving Bijections of Euclidean Spaces." 2026. https://doi.org/10.5281/zenodo.22346412.

Cite this as:

Weisstein, Eric W. "Darboux Map." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/DarbouxMap.html

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