[EM] Fwd: MMV and resolvability
Anders Kaseorg
andersk at MIT.EDU
Sat Dec 7 21:27:40 PST 2013
On 12/07/2013 12:49 PM, Michael Ossipoff wrote:> Two things:
> 2. It isn't just by my own wording, that MMV doesn't have the probem
> that you (Anders Kaseorg) described. Prabhakar's wording, it seems to
> me, doesn't have that problem either. Here is what Prabhakar said:
>
> [quote]
> (i) If a matchup later in the list conflicts with the
> previously-determined order, the latter matchup is superseded
> (ignored).
>
> (ii) In the even unlikelier case where several matchups with
> same-size majorities conflict with each other, all such conflicting
> matchups are ignored (though any non-conflicting matchups of that
> size are still included).
> [/quote]
This could be interpreted either way, depending on whether operations
(i) and (ii) are supposed to happen simultaneously or sequentially. It
would be clearer if (ii) was written “…several _remaining_ matchups with
same-size majorities…”.
On 12/07/2013 07:56 PM, Michael Ossipoff wrote:
> Better brief definition of MMV (which I formerly called DED-RP):
>
> Keep every defeat that doesn't contradict (by being in a cycle with
> them) a set of defeats that are all at least as strong as it.
>
> [end of brief MMV definition]
This brief definition seems too brief. In my example
5/2: A > C, B > C, C > D
4/3: A > B, B > D, D > A
the defeat A > B is in a cycle with a set of defeats that are at least
as strong as it (A > B > D > A). But it sounds like you agree that we
want to affirm A > B. In order to do that, we need to disqualify D > A
_before_ checking whether to affirm A > B. Perhaps you think that this
order of operations is somehow implicit, but given that Eric Gorr’s
calculator works differently, I think it’s important to be unambiguous:
“Affirm every defeat that doesn’t contradict the set of strictly
stronger affirmed defeats and equally strong ‘admissible’ defeats, where
a defeat is ‘admissible’ if it doesn’t contradict the set of strictly
stronger affirmed defeats.”
Anders
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