Let me explain my point further by giving an example of what knowledge exactly are we talking about here, that engines and endgame tablebases possess, but in much more concrete form, which raises the question of software possibility to extract it from them in an abstract form, like I will present here, without using software.
Pawnless endgames with major pieces, are a good start because some of them are most elementary checkmates, simplest patterns to describe, such as K+Q vs K and K+R vs K.
In both cases, the lone king must be forced to the edge (or to the corner) of the board in order to get checkmated, due to a lack of other pieces (its own or its opponent’s) that could constrain its mobility additionally in sufficient way, if they were present.
This can always be achieved by squeezing it from the center, by placing our king in opposition (an even simpler concept which also requires explanation/description), and checking it from the side, with the major piece. Actually, this is needed only in the rook case, queen alone can squeeze the opponent’s king to the edge by itself, without a help of its own king, one should only watch out not to squeeze it too much, into the corner, where it would be stalemated. But as queen can be underused, ie used as a rook, we can explain the rook pattern as applicable for both major pieces, and get back to show how queen can be used better, according to its full potential.
In order to prepare opposition, major piece is placed to a line adjacent to opponent’s king (obviously not within its reach of one square to avoid capture), chosen opportunistically so that squeezing takes minimal number of moves/lines from the target edge.
If the opponent’s king is strictly in the center (d4, e4, d5 or e5), then this strategy requires more moves to accomplish the goal in comparison with cases when it is nearer the edge, and we can choose d or e file, or 4th or 5th rank, to cut the board in two parts, depending on where exactly is the opponent’s king, and where is our king, which should be on the other side of the board than opponent’s king, ie major piece is also supposed to be placed on the line that is between the two kings, and it should stay there until its own king approaches the line adjacent to that chosen for the major piece. This is always possible because of two reasons, opponent’s king cannot approach our queen in order to squeeze it from the line it occupies, and rook is much faster piece than the king, so it can always maintain the safe distance from opponent’s king staying on the same line.
When the king arrives on the supposed line, next to the line occupied by its major piece, two lines far from the opponent’s king, it can force the opposition (position when it is standing on the same perpendicular line as the opponent’s king, two squares away from it) moving along the same line due to the fact that opponent’s king cannot run away from our king (assuming we take a stronger side for the purpose of this explanation) along the same line further than the edge of the board, and due to the fact that our major piece can easily “lose” a move if needed (staying on the same line, and on the same side of it, far from both kings) when opponent’s king changes direction, and starts moving towards our king, placing itself one square away from opposition. After that major piece move, lone king must either continue towards our king and step into opposition, or continue running away along the same line which may be not possible if it is already at the edge.
When it steps into opposition, our king covers all three squares in front of it, so when it gets checked from the side by the major piece, it must step back one line, as it cannot stay on the same line, and if there is no line to step back, then it is checkmated. Of course, it there is, our king advances one line following our major piece that already advanced, and the procedure continues. And if at any time the lone king steps back voluntarily one line without being forced by side check and opposition, the major piece first takes advantage of that by advancing one line, and only then our king follows.
It must be noticed that running away from our king towards our major piece does not make any problem, because rook can move along the same line to the other edge to avoid capture, transposing into previous case in which opponent’s king can either move toward the edge, or towards our king (which now stands again between our rook and opponent’s king, in terms of lines perpendicular to the chosen line along which the rook moved), while the queen does not even have to move, as it cannot be captured.
That explains how queen can be used better, to squeeze the lone king towards the edge without engagement of our own king, which joins forces with the queen only at the very end, by giving support for queen’s delivering kiss of death to opponent’s king at the edge of the board.
So, in the case of queen, major piece can not only stay on the line adjacent to opponent’s king, but it can also squeeze it along that line towards the edge, forming each time horse like L shape configuration between two pieces, ie one rank two files away, if moving along the rank, or one file two ranks away if moving along the file, if lone king tries to keep the position on the same line. In that case it will soon reach the edge, when it can be cut off by queen to stay permanently on that edge, until our own king arrives near, or, it will have to step back one line, and then queen will advance one line maintaining the L shape configuration, regardless of whether the king stepped back diagonally towards the center, which is the most resilient option, or in any other of two possible ways. Basically queen follows the lone king by making “king like”, one square moves. Eventually this will also squeeze the king to the edge.
Of course, if the king steps back into a corner, queen will not follow the same L pattern, instead of that it will move one square further on the penultimate line, leaving two squares free on the edge line for the king to be able to move, until its own king comes near to provide support for the final blow, which can be frontal contact of queen and lone king, diagonal contact if the lone king is in the corner, or contactless side check while its own king constrains the lone king in the manner of opposition.
Notice how the whole explanation is devoid of any concrete position, which makes it abstract, but not any less valid or precise than that what an engine or an endgame tablebase can present. Moreover, this is how human mind learns and memorizes these things.
OK, although these endgame concepts are basic, they may be not the simplest ones to describe, but others are either less basic and more complex to start with, like K+B+N vs K, or are built upon these (because they include pawns, which are promotable), so in a way they include the complexity of these presented, so I chose them.
But any abstract explanation of these two endings cannot be significantly different from this, although it can be surely more concise, simpler, precise and elegant. Probably if I could have expressed it in a not yet existing CCDL (Chess Concept Description Language), instead of in natural language, it would have been so. Although I made an effort to make it precise and concise, I did not achieve the result similar to what you get when you write in a domain specific strict language.
However, I cannot get that from DecodeChess either, which misses such patterns in its repository of human knowledge, and therefore cannot recognize them and present them, let alone create such explanations automatically as a result of machine learning and store it to knowledge repository, in order to be able to use them later in its explanations. This is a screenshot of what I got for such a position that clearly demontrates my point:
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