On the subject of inplace the synopsis currently states Although quicksort is usually not implemented as an inplace sort it is possible to create such an implementation  The reference cited actually states the opposite so this needs to be changed at any rate but from what I gather it was originally changed from stating that QS can be done inplace because when the recursion is factored in the amount of storage used is not constant this change was done due to the text of the Inplacealgorithm article  Whether the present article classifies QS as inplace doesnt matter to me but either way the text of the introduction needs to be changed  I leave this to somebody who feels strongly about making a case for whether QS is in fact inplace