Practical Chess Notebooks 7: Calculation Problems
 All chess is steeped in analysis and calculation. Combinations and tactical play in particular require a high dose of calculation. We are talking about those positions in which, given the acute nature of the fight, the value of each tempo is crucial or very high. Calculation was studied specifically in Chapter 6 of Chess School 2, Reading the Position, and more specifically in Section 4, Calculating Variations. The student should bear in mind that, when solving the exercises, he is not asked to decipher each and every move in the game (which are sometimes included right at the end for documentary purposes), but only those that, say, lead to a decisive advantage for one side (+ -, - +), or forced draws (=) when appropriate. There are exceptions (and in this regard the guidance of an instructor, or the reader's own common sense, is important), because if the first one or two moves produce this judgment, the solutionist is expected to provide additional concrete lines that enrich the solution. Chess is not a mathematical science and admits several interpretations.
 There is only one formula for progressing in chess: playing as many tournaments as possible, along with theoretical study and analysis of one's own games. The ideal complement to this formula, as many Grand Masters recommend, is for the player to develop and perfect his tactical and strategic ability by solving numerous exercises, specially selected for their usefulness. Like the ones we offer you here.