simultaneous multiple key sorting algorithm

Manfred Nowak svv1999 at hotmail.com
Sat Jan 28 07:10:08 PST 2012


Andrei Alexandrescu wrote:

[ About ranks]
> Actually they need to be computed.

Then the problem is still too unclear.

> I think it's possible to find cases where
>    rank(a, k1) + rank(a, k2) < rank(b, k1) + rank(b, k2)
> but
>    alpha * a.k1 + beta * a.k2 > alpha * b.k1 + beta.k2.

Of course. Especially if the a, b, ... are sortable only partielly. 
But if the ranks are known, the problem can be finished with the 
linear median algorithm.

> One potentially confusing issue is that importance applies to
> rank, not features.

Do you mean that
  alpha * rank(a, k1) + beta * rank(a, k2)
has to be extremized for all `a'?

Again: the problem is still unclear.

-manfred


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