Rule-23 The position shows nine Pawns standing on the squares where they stood at the start of the game: a2, b2 e2, f2, h2, a7, b7, c7, f7; they have not moved yet; the other seven Pawns have advanced during the progress of the game. The Pawn d4 has two possible moves: to advance to d5 or to capture e5. The Pawn c3 has only one possible move: to advance to c4. About four centuries ago, the rule was introduced that Pawns in their initial position and which are not blocked may advance one or two steps according to the plan of the player. This rule made the game more lively, and therefore the Chess world accepted it over time. For instance, Pawn a2 may advance to a3 or to a4 in one move. With this rule a difficulty arose. Its object was to accelerate the pace of the Chess events and to add to their variety, but sometimes it betrayed the obvious rights of the opponent. To illustrate this point, look at the two Pawns f2 and g4. The Pawn g4 stands on guard over f3. If f2 advances to f3, g4 c...