[EM] number of possible ranked ballots given N candidates

[Jobst Heitzig]

Sorry, typo:

I wrote:
> as in X>Z,Y>Z,X?Z
but meant X>Z,Y>Z,X?Y of course. As a Hasse diagram:

  X     Y
   \   /
    \ /
     Z

Not to be confused with X=Y>Z:

    X=Y
     |
     |
     Z

More complex example: A>B>C>D,A>E=F>D:

     A
    / \
   B   \
   |   E=F
   C   /
    \ /
     D

Jobst