The Strategy of Chess. Edward Lasker
be an obvious miscalculation, for the value of the defending pieces is smaller. [Footnote: It is difficult to compare the relative value of the different pieces, as so much depends on the peculiarities of each position, but, generally speaking, minor pieces, Bishop and Knight, are reckoned as equal; the Rook as equal to a minor piece and one or two pawns (to have a Rook against a minor piece, is to be the "exchange" ahead). The Queen is equal to two Rooks or three minor pieces.]
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8 | | | | | #R | | #K | |
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7 | | | #P | | #R | | #P | #P |
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6 | | #P | |#Kt | | #P | | |
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5 | | | | | | | | |
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4 | | | | | ^P | | | |
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3 | | | ^P | | | |^Kt | |
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2 | ^P | ^P | ^B | | | | ^P | ^P |
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1 | | | | ^R | | ^K | | |
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A B C D E F G H
Diag. 5.
Chess would be an easy game if all combinations could be tested and probed exhaustively by the mathematical process just shown. But we shall find that the complications met with are extremely varied. To give the beginner an idea of this, I will mention a few of the more frequent examples. It will be seen that the calculation may be, and very frequently
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8 | | | #R | | | #R | #K | |
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7 | #P | | | | | #P | #P | #P |
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6 | | #P | #B | ^R | |#Kt | | |
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5 | | | #P | | | | | |
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4 | | | | | ^P | | | |
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3 | | ^B | ^P | | |^Kt | | |
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2 | | ^P | | | | ^P | ^P | ^P |
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1 | | | | | ^R | | ^K | |
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A B C D E F G H
Diag. 6.
is, upset by one of the pieces involved being exchanged or sacrificed. An example of this is found in Diagram 6; KtxP
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8 | | | | | | | | |
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7 | | | | | | | #P | #K |
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6 | #B | #P | | | | | | #P |
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5 | | | #P | ^P |#Kt | | | |
|———————————————————|
4 | | | ^P | | | | | |
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3 | | | | |^Kt | | ^B | |
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2 | ^P | | | | | | | ^P |
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1 | ^K | | | | | | | |
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A B C D E F G H
Diag. 7.
fails on account of R X B; this leaves the Knight unprotected, and White wins two pieces for his Rook. Neither can the Bishop capture on K5 because of R X Kt. leaving the Bishop unprotected, after which BxKt does not retrieve the situation because the Rook recaptures from B6.
A second important case, in which our simple calculation is of no avail, occurs in a position where one of the defending pieces is forced away by a threat, the evasion of which is more important than the capture of the unit it defends. In Diagram 7, for instance, Black may not play KtxP, because White, by playing P- Q6, would force the Bishop to Kt4 or B1, to prevent the pawn from Queening and the Knight would be lost. A further example of the same type is given in Diagram 8. Here a peculiar mating threat, which occurs not
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8 | | | #B | | #Q | #R | | #K |
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7 | | | | |#Kt | | #P | #P |
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6 | #P |^Kt | | | | | | |
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5 | | | ^R | |^Kt | | | |
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4 | | | ^Q | | | | | |
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3 | | | | | | | | |
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2 | ^P | | | | | | ^P | ^P |
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1 | | | | | | | ^K | |
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A B C D E F G H
Diag. 8.
infrequently in practical play, keeps the Black Queen tied to her KB2 and unavailable for the protection of the B at BI.
White wins as follows:
1.