A retraction is a continuous map of a space onto a subspace leaving each point of the subspace fixed.
Alternatively, retraction can refer to withdrawal of a paper containing a mistake.
A retraction is a continuous map of a space onto a subspace leaving each point of the subspace fixed.
Alternatively, retraction can refer to withdrawal of a paper containing a mistake.
This entry contributed by Jonathan Sondow (author's link)
Sondow, Jonathan. "Retraction." From MathWorld--A Wolfram Web Resource, created by Eric W. Weisstein. https://mathworld.wolfram.com/Retraction.html