As explained in the first part of this series it is only necessary to calculate in positions where there are forced variations and the possibilities are limited. It is impossible to calculate when the possibilities are unlimited.
In these situations the first logical step is to select a series of candidate moves, so we can immediately conclude that in order to calculate well we need to select good candidates moves. This process is extremely important and there are techniques that will help you to improve it.
One of the first authors discuss the idea of candidates moves was Alexander Kotov, in his famous book Think Like a Grandmaster. However Kotov proposed creating a complicated tree of variations, which is inefficient. I believe that in chess there are no ready made recipes, and instead it is orderly and logical thought that will lead us to success.
Many times in order to find good candidates we need to have good candidate ideas. These candidate ideas will lead to a limited number of candidates, and only the analysis of these will allow us to know if it is necessary to find new candidates. A concrete example will serve to clarify all this:
Choosing candidate moves correctly is the basis for success in calculation, however the correct move in a particular position will not always be among the first candidate move that we will analyze. Even the strongest GMs don’t achieve this all the time, sometimes it is necessary to expand the number of candidate ideas and moves.
This statement raises the question about when is the time to expand the candidates? As I said earlier there are no exact recipes or algorithms when calculating, but I can tell you a series of recommendations: First you must select very few candidates. Sometimes it is enough to select a single move since the best move in the position may be obvious, or so it seems. Most of the time we choose 2 or 3 moves to consider, and very rarely more than that. In principle we should limit ourselves to a serious analysis of these chosen alternatives. Many times, through this analysis we are going to conclude that one of these alternatives is the best, but it is also possible that we will not reach a definitive conclusion. When we intuitively feel that in the position we can achieve more than what we have found by calculating the first candidate move, we must stop concrete analysis for a moment and take a fresh look at the position, without any preconceived idea, and ask ourselves: Are there other options? Is there something that I’m missing? Are there other candidate moves? This way we will find the hidden resources of the position. Here is a very simple example of this:
Successfully selecting the candidate moves is the basis of any good chess calculation. Meanwhile expanding the candidate moves is a very important technique to calculate correctly, since there are positions where the winning or saving resource is hidden. The difficult thing is not the concrete calculation of moves but the finding of this resource. Once found, calculating it will not take much time.