29 Jul
2004
29 Jul
'04
10:51 p.m.
On Fri, 30 Jul 2004, Fred W. Helenius wrote:
At 11:51 PM 7/29/2004, Thane Plambeck wrote:
I'm confused. Shouldn't there be 4 \choose 2 = 6 permutations at distance one?
Perhaps Dan means to limit the transpositions to transpositions of adjacent elements; at any rate, that definition results in the same numbers for S_4.
In that case, this is the metric Diaconis calls "Kendall's tau" in the book I mentioned previously. Apparently this metric has a long history. See Diaconis' book for pointers. --Edwin