Chess will never be solved, here's why

That's not what I meant by endgame. I meant endgame referring to a combination if pieces left that doesn't involve anymore transformations/conversions to simpler combinations, such as 2 bishops vs knight, queen vs rook, queen + knight vs knight + bishop + rook, 2 knights vs pawn, rook + knight vs 2 knights...etc, some of which can take hundreds of moves to win with perfect play. Middlegames might have multiple endgame that it can end up going into, there might be thousands of possible piece combination endgames that cam result from the middlegame. By "middlegame" I literally just meant the phase between opening book moves and where tablebases are needed.

The definition of an endgame is not that precise.

You're right, and even a couple of those "precise move" tablebase endgames, technically involve a trivial capture at some point which is a transformation, but I was just trying to distinguish between "middlegame" and the point at which it comes down to pure geometry and exact moves matter in one specific type of endgame. Pawnless endgames might be a better distinction since no new pieces can appear from promotion. It comes down to the pure geometry of the remaining pieces themselves, such as 2 bishops vs knight. The most complex endgame, Queen + Knight vs Rook + Bishop + Knight has no pawns and can take over 500 moves to force a win. In the middlegame it's more vague strategies in calculation such as "putting pressure", "forcing opponents position to become cramped", "having a good pawn structure", "dominating the center", "heading toward the side their king is on"...etc, not exact calculation from a tablebase.

@Elroch - I've also considered that 'one move' thing. In multiple ways.
In theory - each advancing tablebase could then only have to 'deal' with a one ply depth to get to the next already-established tablebase position?
No because that would only work with captures.
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There are so many ways of classifying positions.
And it seems that if a 'one ply deep' method of approaching tablebase generation could be applied - then there would not have been so much struggling over a period of years to proceed from six pieces to seven pieces?
No. Because if that idea could have 'fixed things' - then it would have.
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Idea: (I'm confident they applied this obvious idea) - and that is - as they proceed backwards from just two Kings on the board - they use a 'hierarchy' of positions to create starting points.
And even a hierarchy of hierarchies.
So for example to go from six pieces to seven pieces - perhaps they used both material and position hierarchies something like this:
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First add one pawn on its original square. Both colours.
Start with edge-pawns (fewer options)
Then go to pawn placed on its third rank of the board.
But with adding one pawn at least four 'attribute variables' begin to develop.
Yes 'attribute variables' is probably bad english.
But 'criteria' wouldn't seem to fit here.
You're a statistician so you would know the correct statistical term or terms for the following:
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1) the pawn does or does not have a double pawn move available. Note that a pawn on its home square might not have that option available.
2) the pawn can or cannot move at all.
3) the pawn can or cannot capture at all.
4) the pawn can or cannot promote at the time.
and then 'attributes' (yes might be the wrong word.)
white or black pawn.
who is on move.
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After adding a single pawn tablebase (one ply deep) is generated -
then adding a single knight Instead could be done (or maybe was/is done)
starting with a knight in each of the corner squares (fewest options)
then a N on an edge non-corner square with max 3 squares available.
then an edge-knight with 4 such squares available.
Note a knight at g2 and b2 and b7 and g7 still only has four squares available but is then an interior-knight.
Then knight that has six options and then finally 8 options. (no 7's or 5's but there is a '3').
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and then moving on up towards a Queen instead added at the end.
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basic 'demarcation': Is at least one capture available on the board?
Should that be another 'adding' priority?
It seems yes.
Because otherwise the start of the higher tablebase doesn't connect to the previous one!
For project purposes that seems almost more important than whose move it is !!
And does the capture have to be available to the side on move?
In the first hierarchy yes.
In the second - its the other side.

It's important to distinguish between GENERATION of a tablebase and ACCESSING a tablebase.

The generation process consists of iteratively generating all the positions that will reach a win for one side with perfect play. Here "perfect play" has the stronger meaning that the winner always wins as fast as possible (assuming perfect defense) and the loser always gets mated as slowly as possible (assuming perfect attack). Rather than me trying to describe it, here is the description selected by the wiki authors, from Tim Krabbe.

@Elroch
from your post:
"The generation process consists of iteratively generating all the positions that will reach a win for one side with perfect play."
But first you would have to generate positions in the first place.
I'm thinking that that is the primary process - getting to 'win' is a kind of 'gravy'.
But yes that Wiki link you posted points to a nice article.
In full form: https://en.wikipedia.org/wiki/Endgame_tablebase#Step_2:_Evaluating_positions_using_retrograde_analysis<br<; a=""> />-----------------------------
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Also my question about 'attribute variables'.
But you don't have to answer of course. Questions aren't thunder.
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Regarding 'iteratively' that pertained to some of the other points in my post.
Note that Alpha Zero was prevailing for a while because it was an improvement in 'prioritizing calculations'.
And also adding - that the forum subject of 'solved' pertains to the game itself - not just computer projects.
In other words the forum subject pertains to how players go at the game - as opposed to how chess software goes at it.
Its a much broader topic than might appear.
Note that the Opening Poster referred to this very point in his opening post.
And he referred to it Heavily.
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Example: Stronger players will and do tell weaker players when coaching how to adjust to speed chess: 'Look at checks and captures first.'
In other words prioritize primary tactics.
But why wouldn't one do that with slower chess too?
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Connection: in tablebase projects - prioritize positions that contain at least one capture option. And start with positions that have just one.
Because that is the revolving door between levels of tablebases.
Is 'aesthetic effect' the right phrase to describe this next point?
In considering computer projects to solve chess - the entire game is considered in a kind of overview. An overview that computers would perhaps not be capable of.

huh

@Elroch of course your musings are not boring.
Boredom is usually the fault of the bored person.
Like being blocked is usually the fault of the blocked person.
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You stated that its 'easy' to generate all positions with whatever number of pieces - if I have that right.
That part is obvious and incidental though.
The point is: what positions to prioritize - or concentrate on first.
Then you mentioned about 'mate in x' or whatever.
Which isn't my point.
Because that almost relates to circular reasoning.
Because in the initial stages you don't know what those positions are.
Hence my suggestion: start with positions where there's an obvious 'feature' or 'certain attribute' or 'meets criteria'.
For example - generate all positions where there's a capture available - but only one capture.
So there's a two way door between such positions and their more basic tablebases. The most minimal door.
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You could argue that the project people have covered all that.
That they've considered all the 'vicissitudes' in this project to counter the 'viscious' number of legal positions with each number of men on the board.
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the opening poster here apparently closed his chess.com account two days after posting the opening post.
He had been with chess.com just 11 days. Since Jan. 5th 2022.
Posted and started this forum Jan. 16th 2022.
Closed his chess.com account Jan. 18th 2022.
Idea: he closed his account because of the reaction he got in this forum ... ??

I was just looking at the posts that were made those first three days in this forum.
Saw this excerpt from Martin:
"There is no 50 move rule, 75 move rule, 3 fold repetition rule or 5 fold repetition rule in the FIDE basic rules of chess. Those rules now apply only to games covered by competition rules. The 50 move rule and 3 fold repetition rule were removed from the basic rules in 2017, the other two were never in. Prior to removal the draws had to be claimed anyway so games of any length were permissible."
'competition rules'.
'basic rules'.
Terminology again.
Yes - Martin probably stated more than once in what situations FIDE 'competition rules' apply and what situations they don't.
If I saw it - I forgot.
But does that mean people entering the forum would know?
Does it matter?
Short answer: slightly.
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Anyway idea - after three days of postings the forum took a kind of trajectory the opening poster had never intended and he closed his account.
Does that part matter?
No.
But what about what he intended?
Does that have any significance?
Maybe. Something to do with time investment.

Not true of all tablebases. True of DTM or DTM50 tablebases in basic and competition rules chess respectively, but not true of DTC tablebases in basic rules chess or DTC50 or DTZ50 tablebases in competition rules chess for example because their objective is not to minimize the number of moves to mate. They don't produce mates of a consistent length.

I'm suggesting the 'moves to mate' is cart before the horse.
Two types of positions: those that are doorways between classes of positions (at least one capture available) and those that aren't.
Is there a third? Well it becomes 'game tree'.
There's at least one capture available but it isn't played.
fourth and fifth: all positions with checkmate on the board and all positions with stalemate on the board.
sixth class: all positions where you couldn't mate because there's not enough material. Example: K+N versus Lone King. Or K+B. K+2 bishops moving on the same color squares. No checkmate possible.

The "rather obvious" positions can be omitted, like king + 3 knights vs Long king, king + 4 bishops vs king + 1 knight..etc, king + 2 queens vs 1 rook..etc, as those are easy wins for a basic engine and don't need a tablebase. I read that originally king + 5 pieces vs king and other obvious ones like above were omitted in the 7 piece tablebases initially, but then decided to include them 6 years later.

Interestingly, while you can generate most of each new tablebase file from retrogade moves from previously generated ones (backward transitions) followed by more of the same, you would always need to add all the positions with mate on the board and stalemate on the board anyhow, since they are not a backward move from anywhere. I think there is a way of generating just the positions that are mate or stalemate on the board for each given set of material (but it's not that simple).

One thing retrograde analysis does not do is come close to checking legality. Making backward moves can easily get to a position unreachable from the standard starting position. This happens more when you have more pawns.

Only 10 black pieces need to be captured to reach that, think it's legal?

@Elroch
"Making backward moves can easily get to a position unreachable from the standard starting position."
But you have to allow that for the time being.
As the tablebases proceed - that might become much easier for whatever 'algorithm' to be developed that crunches that.
In the scenario I'm thinking of - computers generate various types of positions with 8 men on the board before even dreaming about 'mate in x' or 'unreachable legally'.
So far I thought of five types but three of them are kind of final.
Checkmate and stalemate and King + 6 bishops moving on the same color squares.
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The other two are: at least one capture available (doorway to the 7 piece tablebases) and no captures yet available (no doorway yet).
Of those five types only two can be generated from the 7 piece.
Point: You don't have to use the 7-piece to originally generate those 8-piece with at least one capture on board.
But you might be able to use the 7piece to 'solve' some of those 8 piece positions. In other words 'forward motion)
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@Elroch - you don't necessarily have to use a 'reverse move'. To generate an 8 piece. Would apply in both situations.
Consider just adding whatever to the seven piece without a reverse capture.
Then the 8-piece doesn't have to contain a capture option.
Consider it for a minute.
Do any two positions thus compared have to be 'incompatible'?
No.
It would take multiple moves to get back to the seven piece you just used to create the 8-piece.
Could there be 8-piece positions where you 'couldn't get' to that position?
But then it could lead to some other 7-piece position or positions.
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I would rather have started with 3 and 4 piece ... but okay.
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what could be 'Group six'?
Lopsided lone king situations.
You can't get from 8 piece to seven piece unless the lone King captures.
And if he does the only way he draws is if the remaining six pieces are all bishops remaining on the same color squares. Or the result is stalemate because the other sides other pieces are locked by his pawns.
Which I already covered on both.
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So group six is all wins but with no mate on board.
And with one side with just his King.
Speed up the project by skipping those?
Yes - or assign them to a different computer to determine the 'mate in x'.
Wow - even a computer could complain about that?
What would that computer say?
'Hey we know these are wins! What's the idea?'
Programmer: Stop playing human.

An interesting factoid to note in terms of how many pieces possible...6 pawns from each side can pass each other without capturing other pieces:

trust me i know

Well spotted - it needs another white pawn on a7 AND a single black piece or pawn on the board. eg

That could easily have been a promoted bishop, you should join the "illegal position contest" thread, people make more and more complex illegal positions where the proof that it is illegal is extremely subtle.

Such as, "well in order for the bishop to get to this square it had to get around these pawns this way, which means these pawns had to have moved before the knight got here. But for the knight to have gotten here, the king and queen couldn't have gotten to these squares behind the rook, without the king passing through a check that is impossible"....the goal in the thread is to make the most subtle illegal positions that are harder and harder to figure out the reason why!