[Retros] Proof games with loss of tempo

[Francois Labelle]

On Mon, 2012-03-19 at 18:09 -0700, Kevin Begley wrote:

> I'll second what Andrew has said -- congratulations Francois... PG b)

> is quite remarkable!


Thanks Andrew and Kevin! I didn't expect the problem to be that good! It
turns out that there are 34 such examples with n=4.5, listed here:
http://wismuth.com/chess/diagrams/tempo09-3.txt

I just picked the first one. Maybe someone can look at the set and say
whether they're all really the same idea. It turns out that White can
use the other bishop or the queen. There are 16 examples with each
bishop, and 2 examples with the queen.

A surprising fact is that the 1-1-1-1-solution task is impossible with
n=5.0, so these PGs with n=4.5 might indeed be very special.

On Tue, 2012-03-20 at 08:44 +0100, Joost de Heer wrote:

> On Mon, March 19, 2012 06:44, Francois Labelle wrote:

> > t=3.5 ?

> 

> Michel did this in 2000:

> http://www.softdecc.com/pdb/search.pdb?expression=PROBID='P1000618'

> 


Thanks Joost! This means that all possible tempos of 4.5 moves or less
have been achieved. Is there a proof that > 4.5 is impossible?

	Francois