Ruy Lopez that after the common retreat 4.Ba4, Black will have the possibility of breaking a future pin on his by playing ...b5. White must take some care not to fall into the Ruy Lopez, Noah's Ark Trap, in which Black traps White's on the b3-square with a ...a6, ...b5, and ...c4 pawn advance on the . Ercole del Rio, in his 1750 treatise "Sopra il giuoco degli Scacchi, Osservazioni pratiche dell'anonimo Modenese" (On the game of Chess, practical Observations by an anonymous Modenese), was the first author to mention 3...a6. However, the move became popular after it was played by Paul
Tactical decision game fictional. If the scenario is based entirely upon a reliable historical narrative, a tactical decision game is also a "decision-forcing case". (Such an exercise may also be called an "historical map problem".) However, if any of the elements in the scenario of a tactical decision game is fictional, then the exercise is a kind of "fictional decision game". In Chapter 14 of "The Prince", Niccolò Machiavelli tells the story of the Greek general Philopoemon, who made extensive use of tactical decision games. “Philopoemon, Prince of the Achaeans, among other praises which writers have bestowed on him, is commended because in