About

Stability Analyzer is a tool to provide you additional measure of chess positions (in addition to standard score), called stability score (0-100). It describes how easy is it to break the position. Namely, if you were to do reasonable moves, would the score be kept the same? Or is the position lies on thin ice?

The tool has seamless integration with Lichess. For this you should install the extension.

Note: No processing is done on your device. All analysis is performed on our servers. As this is in alpha stage, the servers are not guaranteed to be operational.

Rationale

For half a century, computers have been utilized to analyze chess positions. Throughout this period, a single measure was established as the only numerical metric which is used in computerized analysis. I refer to the infamous centipawn loss of course, that signifies how good or bad a position is (in terms of pawn advantage).

This is the case even though this score fails to account for some very important aspects of the position. For instance, there could be a position that is only good because of an obscure 10-moves line no human, not even the world champion could find. The absolute evaluation has no meaning in this case. Or the position could look calm and solid, perhaps advantageous, but one has to play very precisely in order to maintain the advantage. While analysing a position, a player should be able to discern whether it is his opponent who would struggle to find good moves down the line, or he is. Ideally, that information should be readily available to him.

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In all the cases mentioned, one could argue that the position is not stable. Indeed, quite often keeping the position stable is even more important than playing the absolutely best move. Or rather, the stability of the position matters more than the absolute evaluation. That is of course, from human perspective, as we are generally very bad at playing positions computers excel in.

However, positional preferences vary among players. While some prefer less stable (more tactical) positions, others seek solid ground. The interesting bit concerns positions which are only stable for one side, but unstable and tricky to play for the other side. This kind of imbalance is what high level chess players strive to achieve.

Hopefully, by now you would have grasped the intuition behind the concept. To understand it deeply one would have to know the mathematical details of the method. However, so to provide some formal sense, the notion can be thought of roughly as The expected percentage change in evaluation resulting from playing a random reasonable line of a certain depth.

What are reasonable moves? Those are in principle human moves, or intuitive moves. It should come as no surprise that computers are perfectly capable of playing human-like moves, as bots in chess.com keep us entertained.

The challenge here lies in devising the method to calculate the stability, and in choosing the right parameters, to have a reasonable performance. While I am quite satisfied with the current state of affairs, it is still far from perfect. But in principle, I think this should demonstrate that such measure is both useful (even in its current state), and of course achievable. And I find it strange, it hasn't been devised before.

There is a pending patent for this method.

How Stability Scores Work

The tool provides two distinct stability scores that measure different aspects of position stability:

Same-Color Stability

This score (0-100) measures how stable your position is for the current player. It measures the stability based on the set of plausible positions that the other player could face(following the current player moves). If that is high , the current player playing reasonably would like not hurt his position (i.e. hard to blunder). The calculation considers worse positions where your score is lower as part of the stability score.

Different-Color Stability

This score (0-100) measures how stable the position is for the opponent. The same logic applies. But this time the initial positions are those after the current play. We calculate stability for each position the playing player will face and average it.

Overall Stability Score

The final (average) stability score is calculated as a weighted average of the same-color and different-color stability scores. The weights are proportional to the number of positions analyzed for each player. Specifically: Overall Stability = (Same-Color × Number of Same-Color Positions + Different-Color × Number of Different-Color Positions) / Total Positions. This ensures that the final score accurately reflects the relative importance of each player's moves in determining overall position stability.

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