Undermining (chess) Undermining (chess) Undermining (also known as removal of the guard, or removing the defender) is a chess tactic in which a defensive piece is captured, leaving one of the opponent's pieces undefended or under-defended. The opponent has the unpalatable choice of recapturing or saving the undefended piece. A possible response is to sacrifice the piece whose defense was undermined before capturing the piece which just took the defender. Kramnik–Topalov in the seventh round of the 2004 Linares chess tournament reached the diagrammed position with White to play. The black knight on a4 is defended only by the black pawn on
When a white horse is not a horse ambiguity of whether "is" means: In other words, the expression "a white horse is not a horse" is ambiguous between "a white horse is not identical with a horse" (true, because "white horse" is more specific than "horse"), and "a white horse is not a member of the set of horses" (obviously false). The Advocate in the dialogue is asserting that "a white horse is not [identical with] a horse," while the Objector is interpreting the Advocate's statement as "a white horse is not [a member of the group of] horses." An illustration of the alternative uses of "fei" may