Stable partition3 implementation

[John Colvin via Digitalmars-d]

On Wednesday, 22 July 2015 at 16:59:29 UTC, Xinok wrote:
> On Saturday, 11 July 2015 at 02:56:55 UTC, Timon Gehr wrote:
>> [...]
>
> I understand now. I had never heard of an iterated logarithm 
> before. I took the asterisk to mean some constant, like a wild 
> card if you will. Sorry for the confusion.
>
> I wonder if the true O(n) algorithm is still worth pursuing. 
> Although log*(n) may only be a factor of 2 or 3, the O(n) 
> algorithm may have a small constant factor which makes it 2-3x 
> faster.
>
>> [...]
>
> I get that much now, but this paper is still way above my head. 
> There's some notation in the sample code that I don't 
> understand. In this statement:
>
> e <- #{ j : L[j] = x, 1 <= j <= n }
>
> I'm not sure what the pound # signifies or what exactly is 
> being assigned to e. I'm assuming it performs some operation on 
> the set, like "max", but I'm not sure what.

I haven't looked at the paper, but # followed by a set often 
means cardinality, i.e. (assuming the set is is finite) the 
number of elements in the set.