BOOK 4 - TACTICAL ENDINGS
 We call those tactical endgames in which the struggle, usually technical, of this last phase of the game is influenced by threatened kings, or by combinatorial sequences to promote a pawn, exploit a certain advantage, or discover a surprising saving maneuver. In other words, endgames in which tactical play predominates, because they involve sacrifices or uncharacteristic combinatorial elements, when there are few pieces left in the game. The School of Chess manuals (1 and 2) don't study tactical endgames as such, but when studying combinatorial figures (chapters 5 and 7 of SC, chapter 2 of SC 2) they include several examples that can be catalogued as such.
 In any case, this is not a technical topic that is studied systematically in textbooks, but this book is more than justified by its considerable practical value: the positions will give the chess student a greater perspective and insight when facing endgames with similar ideas (which here are very varied and, in many cases, very original).
 Only one formula is known for progressing in chess: play as many games as possible, together with theoretical study and analysis of the games themselves. The ideal complement to this formula is, as many great masters recommend, for the player to develop and perfect their tactical and strategic skills by solving numerous exercises, specially selected for their usefulness. Like the ones we offer here.