byakuugan's contribution prompts me to mention something similar that I've been thinking about for more years than I care to mention now.
The sub-7-man (s7m) EGTs, by my reckoning, contain values and depths for some 3,409,699,385,208 chess positions: that's 3.4*10^12 for short!
Not a set of information that can be managed in the head, so it would be useful to have some landmarks and roadways in this vast terrain.
I've therefore been thinking about how one might assess the significance of various positions, and my idea is that these are given 'notional values' which replace their actual values of 'win, draw or loss'.
For example:
1) KQKR, Philidor (1777), 1k6/1r6/2K5/Q7/8888 w/b: what if this were 'a draw', wtm or btm ... how does this impact White's chances
2) the pseudo-fortress in KBBKN: bN on b2, bK on c2 for example ... ditto ... [and your own favourite positions can go here]
3) a position won by White with wtm, but won more quickly with btm:
- - - - - a 'Squeeze' in at least the UK, and a type B zug in Bleicher/Haworth (2009), qv
http://centaur.reading.ac.uk/4518/
- - - - - is it necessary for the win from the wtm position to go through the btm position
- - - - - this question is answered by setting the 'btm' position artificially to 'draw'
4) consider White about to move at some position in the mainline of a Chess Study
- - - - - White has some moves which are sub-optimal in terms of some metric, say DTM(ate) for now but DTZ would be better
- - - - - if White plays a sub-optimal move, can Black force White back to a position already visited in the study mainline, i.e.,
- - - - - can Black demonstrate that this move is strictly inferior to an optimal move
- - - - - [ the answer is 'no' if that DTx-sub-optimal move is optimal in the metric DTy !]
- - - - - again, this can be assessed by imagining the current position and all previously-visited positions to be 'draw' rather than 1-0.
- - - - - by this means, it is possible to show that a progressing move is 'essentially unique' if not 'absolutely unique' in a study.
- - - - - this is one kind of 'Holy Grail' in the world of studies
5) a computer (again, say 'White') playing otb potentially has a long phase of play of over 50 moves in its winning line, i.e., DTR > 50.
- - - - - maybe the computer it is playing has only DTM or DTZ EGTs, so it's not in the best position to force this long phase
- - - - - White has moves in hand in the current phase, and want to give the opponent the chance to reduce DTR
- - - - - however, White may not wish to revisit some or any of the positions already visited in the game
- - - - - its options can be constrained by setting any positions it doesn't want to visit to 'draw' rather than 'win' and recomputing the EGT.
All of these situations can be handled easily by inserting (into the initialisation phase of an EGT-generator) the setting of certain position to certain values [and remembering that this was done when EGT-validation is done!].
It is a case of computing EGTs for an appropriate variant of Chess, rather than for computing EGTs to a different metric.
Are there any volunteers out there willing to give this a go!?
As I hinted, the DTZ metric is best for this (as repetition cannot return to a previous phase of the game) but DTC and DTM are ok.
Also, as I've argued elsewhere, the assistance of WDL bitbases is useful for generating DTx EGTs as it can prevent the needless and expensive investigation of 'possibly lost positions' in a fully retrograde EGT-generating algorithm.
g