# Problems using an extended notation

If you're reading this, then you probably solved all the standard notation problems and you would like more problems. There are more, but there's a price to pay: you have to learn a special notation. It would be too hard to phrase those problems both concisely and precisely in any other way.

Basically, the extended notation looks like Na8xBb6# with some of it hidden by the symbols ~ and ?. This is explained in detail below, but you can jump directly to the list of problems and learn the notation as you go. There is also a hard version of the same problems.

## Extended notation summary

Each move is composed of 8 tokens. Here are the possible tokens. Underscore represents a space.

(tokens at the finest level)
P a 1 *P a 1 =N .__
N b 2 %P b 2 =B \$__
B c 3 xN c 3 =R +._
R d 4 xB d 4 =Q #._
Q e 5 xR e 5 -_ .+_
K f 6 xQ f 6    .#_
g 7 -_ g 7    ++.
h 8    h 8    ##.
.++
.##

(tokens representing some merging of possibilities)
? ~ ~ xP ~ ~ =? ___
x?     __ +__
*?        #__
?_        ?+_
?#_
++_
##_
?__

## Extended notation tokens explained

To help direct your attention, the tokens corresponding to the information usually available in the standard notation are marked with an arrow (though in the standard notation the starting file is only used for pawn captures).

token 1
-> P N B R Q K      this piece is played
?                an unspecified piece is played

token 2
-> a b c d e f g h  starting file
~                starting file is unspecified

token 3
1 2 3 4 5 6 7 8  starting rank
~                starting rank is unspecified

token 4
*P               capture of a pawn not en passant
%P               capture of a pawn en passant
xN xB xR xQ      capture of this piece
-> -_               no capture
xP               capture of a pawn (en passant status unknown)
-> x?               capture of an unspecified piece
*?               capture of an unspecified piece and not en passant
?_               whether there is a capture or not is unspecified

token 5
-> a b c d e f g h  destination file
~                destination file is unspecified

token 6
-> 1 2 3 4 5 6 7 8  destination rank
~                destination rank is unspecified

token 7
-> =N =B =R =Q      promotion to this piece
-> -_               no promotion
=?               promotion to an unspecified piece
__               whether there was a promotion or not is unspecified

token 8
.__              no check nor checkmate nor stalemate
\$__              stalemate
+._              direct check (only)
#._              direct checkmate (only)
.+_              discovered check (only)
.#_              discovered checkmate (only)
++.              direct and discovered check
##.              direct and discovered checkmate
.++              double discovered check
.##              double discovered checkmate
-> ___              no check nor checkmate (possibly stalemate)
-> +__              check
-> #__              checkmate
?+_              discovered check (possibly double check)
?#_              discovered checkmate (possibly double checkmate)
++_              double check
##_              double checkmate
?__              whether there is check, checkmate, or nothing is unspecified

## Extended notation checkmate problems

Below is a list of checkmate problems only, because they're a favorite and provide plenty of problems. The problems are prefixed by some kind of score. Click on a problem to see the solution.

(nothing)

### ply 6

5.215  3... ?b6- ~~  #
5.181  3... ?d5? ~~  #
5.179  3... ?~~- d4  #
4.262  3... ?b6x?~~  #
3.429  3... ?f6? d4  #
3.408  3... ?f6- f4  #
3.397  3... ?g5? f4  #
3.289  3... ?h4- f4  #
2.455  3... ?f6x?f4  #
2.336  3... ?h4x?f4  #

### ply 7

5.166  4. ?b4- ~~  #
5.102  4. ?b7- ~~  #
4.273  4. Qc4- ~~  #
3.470  4. ?g3? g5  #
3.394  4. ?f4- f5  #
3.384  4. ?g5? f5  #
3.377  4. ?c5? f5  #
3.376  4. ?f5? c5  #
3.375  4. ?g5? c5  #
3.372  4. ?b5? c5  #
3.371  4. ?b5? g5  #
3.357  4. ?g5- d5  #
3.342  4. ?a5? f5  #
3.334  4. ?a5? c5  #
3.324  4. ?h7? f5  #
3.315  4. ?a5- d5  #
2.414  4. ?b5x?f5  #

### ply 8

5.574  4... ?b7? ~~  #
5.097  4... ?a1? ~~  #
4.525  4... Q~~? b5  #
4.258  4... ?g6xQ~~  #
4.122  4... ?a4xB~~  #
4.104  4... ?h2xB~~  #
3.620  4... ?g5? c5  #
3.317  4... ?a3? b4  #
3.268  4... Qb4xQ~~  #
2.436  4... ?a6xBc4  #
2.421  4... ?b5xBc4  #
2.418  4... ?c5xBc4  #
2.418  4... ?c4x?f4  #
2.385  4... ?b4xBf4  #
2.383  4... ?a4x?f4  #
2.381  4... ?g4xBc4  #
2.381  4... ?f4xBc4  #
2.377  4... ?b4xBc4  #

### ply 9

4.660  5. N~~? g3  #
4.147  5. ?f8xB~~  #
4.138  5. ?c7xN~~  #
3.741  5. Ne2x?~~  #
3.632  5. ?d4? h4  #
3.626  5. ?a3? b4  #
3.617  5. ?f4? b4  #
3.608  5. ?b4? h4  #
3.598  5. Q~~x?e4  #
3.575  5. ?h4? b4  #
3.444  5. ?e3- e5  #
3.367  5. ?e6? f5  #
2.533  5. ?f3xNd5  #
2.520  5. ?f3xNf5  #
2.459  5. ?g4xNf5  #
2.421  5. ?c8x?f5  #
2.375  5. ?h5xNf5  #
2.322  5. ?d6xNd7  #

### ply 10

6.052  5... R~~? ~~  .#
5.215  5... ?g5? ~~  ?#
4.291  5... Bf2? ~~  # (used in the Messigny 2004 retro solving tourney)
4.117  5... R~~- h1  #
3.728  5... Nd7xQ~~  #
3.629  5... ?d5? a5  #
3.352  5... ?e6- h3  #
3.321  5... ?f5- h3  #.
3.263  5... ?h1? f3  #
3.237  5... ?f3- e2  #
2.687  5... ?d7xNd1  #
2.684  5... Bg6? f7  #
2.670  5... Bb6? c7  #
2.663  5... Bb6? d4  #
2.533  5... Bg1? d4  #
2.418  5... ?b2x?b4  #
2.384  5... ?f1xQf4  #
2.364  5... ?b1xBb4  #
2.361  5... ?b1xQb4  #
2.354  5... ?a1xNd4  #
2.353  5... ?a1xQd4  #
2.302  5... ?f3xNe2  #

### ply 11

4.657  6. N~~? d3  ##
4.288  6. ?b4x?~~  .#
4.226  6. B~~- h7  #.
4.099  6. ?a8xR~~  #
3.667  6. ?b4? a3  #
3.659  6. Ne2xQ~~  #
3.458  6. ?b4? c5  ?#
3.456  6. ?b4? a5  ?#
3.408  6. ?b4? d6  ?#
3.141  6. ?g7xB~~=N#
2.744  6. ?d2xRg5  #
2.721  6. Ke3? e4  #
2.636  6. ?g4xNd4  #
2.502  6. ?h3xRf5  #
2.490  6. ?f4xRf5  #
2.488  6. ?e4xRd5  #
2.467  6. ?c4xRc5  #
2.459  6. ?b4xRb5  #
2.439  6. ?g5xRd5  #
2.437  6. ?d5xRg5  #
2.413  6. Rf5- g5  #
2.410  6. ?h5xRd5  #
2.407  6. ?b5xRg5  #
2.401  6. Rc5- g5  #
2.394  6. Rb5- g5  #
2.380  6. ?a5xRc5  #
2.369  6. Ra5- g5  #
1.876  6. Qe2xRb5  #