3TA (was Human and ape phylogeny)

[P.Hovenkamp]

At 08:55 AM 4/10/03 +0100, David Williams wrote:

(...)
>My interest in three-item data has nothing to do with any of the above and
>is almost painfully simple. What might be the answer to the simple two
>character problem AB(CD) + AC(BD)? As far as I am aware most (all?) methods
>yield no result, or return the same two trees, as if the solution to 2 + 2
>= 2 + 2. I see the answer as A(BCD) [2 + 2 = 4]. I need no method, no
>matrix, no program (all my MSc students suggest the same answer as well,
>before they learn that computer programs know better). Now, to me,
>something is wrong.

Yes - but where?
When I run this data through Nona using all the usual trappings (heuristic
search settings etc.) I get the following results: two most parsimonious
trees (corresponding with the two trees alluded to by David), consensus of
which is A(BCD). What most people would take to be the result of the
analysis is exactly what David would accept as the result of the analysis.
So why is he not satisfied with the result being produced by a strict
consensus?

Peter Hovenkamp