[Retros] fairy retros

[Nicolas.Dupont at math.univ-lille1.fr]

Hi everybody,

I've had several opportunities to speak with some experts about the actual
status of orthodox proof games. In particular, as a relatively new
componist, I asked whether the exploration of this field may not be coming
to its end.

The answers were various. Around half of the interviewed guys claim "yes",
thinking that almost every challenging task has already been achieved, and
that it only remains to fill some more or less interesting gaps.

The second half said "no", arguing that most solved tasks permit to see
new deep questions emerge, that new strategies are discovered even today,
providing new tools to handle new types of unexpected proof games.

I personally belong to this second category. Let's consider the concept of
"proof game of the future", developped by our common chess friend Roberto
Osorio. A brief look at that classification permits to raise fascinating,
extremely deep problems, probably at the frontier (inside or outside) of
what can be possibly done.

For example the challenging task si(n) vs si(n) is well-known (sibling of
the two pairs of knights), but what about si(n) & si(n) (double sibling of
the same pair of knights) ?

Best,

Nicolas.