[EM] Fw: IBCM, Tideman, Schulze

[Markus Schulze]

Dear Norman,

you wrote (27 May 2000):
> I think that IBCM needs further study before it can
> be considered the equal of our best methods.  Some
> questions that need to be answered are:
>
> 1) does IBCM satisfy clone criteria?
> 2) is IBCM monotonic? (Markus suggested that it might
> not be)

At least in those situations where the IBCM winner is unique,
the IBCM method cannot be manipulated by running clones. You
simply have to ask: "What happens if a single candidate A is
substituted with a set of clones A[1],...,A[m]?" If candidate
B eliminates candidate A in the original situation then he
simultaneously eliminates all candidates A[1],...,A[m] in the
new situation. If candidate C is eliminated by candidate A in
the original situation, then he is also eliminated by every
candidate A[j] in the new situation. Therefore the new
situation is identical to the original situation except for
the fact that where candidate A is eliminated in the original
situation, all the candidates A[1],...,A[m] are eliminated
simultaneously in the new situation. Therefore at least in
those situations where the IBCM winner is unique, the result
cannot be manipulated by running clones.

Markus Schulze
schulze at sol.physik.tu-berlin.de
schulze at math.tu-berlin.de
markusschulze at planet-interkom.de