Lessons learned from a missed move
first of all a heartily thank you to both Likesforests and Chessaholic. You have done me a great service, enabling me to use you as a benchmark. You also convinced me that solving this position ought to be well within my capabilities.
Yet I failed. So how to explain this? Why could I not solve this position, when it was within my ability to project positions, not overly complicated and rather easy to solve by fellow bloggers. I do not know their current rating, but I suspect it does not exceed mine.
IMHO there are two possible explanations. The first one is that I did not visualize and calculate well enough, and may have given up too soon. There certainly is some truth in this explanation. I had visualized up to 4 Kg2, and just did not see the win in this position. Had I however seen this position, not in my minds eye but right in front of me on the board, I probably would have found the winning split. So my ability to calculate from a position 7 ply deep from the board position diminishes too much, to construct a solution I would have found with the same position already on the board.
But there is also another explanation that is even more valid. The split was not a pattern that I had burned into my memory. I may have seen it, but apparently it did not stick. And I suspect strongly that the split is a (well) known pattern for Chessaholic and Likesforests. They spotted this pattern very soon, and Likesforests in his comment confirmed that indeed he was very familiar with it. So for me the big lesson to be learned from this position is: I have to store "the split" into my memory. I do not fear it will not. Just writing this post has left a big impression, and if that were not enough, there is also the excellent marker in Likesforests name "the split".
The reason that I think the second explanation is more valid than the first one is based on research. contrary to average chess players a grandmasters brain activates mainly (or at least much more) his memory. And what else would a gm use his memory for than the search for patterns.
Like every position that I cannot solve, this position is stored by me an a database. After I have finished the book, I will use this database for a second round in which I will again try to solve them. The positions I cannot solve then, will again be stored. I repeat this until I have solved all of them. This is a method which is IMHO much more efficient than the 7 circles. And it has the advantage that it forces you to focus on your weaknesses. Missing a move is never 100% accidental, or just a result of tiredness. It always is a pointer. It either signals that the position is too complicated for you and beyond your ability to visualize and calculate, or it tells that the move is part of a pattern that has not established itself in your brain as well as other patterns.
And though it appears to be just another oversight, I do think that Likesforests missed mate in 1, signals something. It might either be that this mate was not familiar enough for him, and/or that he is inclined to stop thinking as soon he sees that a piece can be taken.
Sloppiness, fatigue, distraction, all increase the chance that you miss the best move, but this occurs the first with those patterns that you have not mastered 100%.