p.boxed
| Pawns start on the 7th rank. Move a knight to promote them.
-h3 Specifications
+h3 Divergences
-ul
- li Chessboard: standard.
- li Material: standard.
- li Non-capturing moves: standard.
- li Special moves: no castling (and no en-passant).
- li Captures: standard.
- li End of game: standard.
+p No castle, no en-passant capture.
p.
- ...(Almost) Only the initial position changes, but this is a very big change.
+ ...Only the initial position changes, but this makes a huge difference.
In particular, castling would be rather pointless so it's disabled here.
En-passant captures are impossible because all pawns already reached 7th rank.
-h3 Note on initial position
+h3 About the initial position
p.
- Since truly random start can allow un-defendable mate in 3 with a knight,
- the kings touch at least one knight in the initial position.
+ Since truly random start can allow a mate in 3 with a knight,
+ the kings have at least one knight neighbor in the initial position.
This allows to move free out of potential check from the very beginning.
p.
- To illustrate this phenomenon, although it's defendable the standard initial
- position allows the attack as 1.Na6 (threatening Nc5-Nd3#),
- forcing the defense Nf3-Ne5. With a knight next to the king you have more options.
+ A less constraining condition would be to require the two knights to stand on
+ two squares of different colors, but it's not enough as proved by the
+ following diagram.
+ White can mate in 3: 1.Nc6 followed by Nb4 threatening both a2 and d3.
figure.diagram-container
.diagram
- | fen:R1BQKBNR/PPPPPPP/N7/8/8/8/pppppppp/rnbqkbnr:
- figcaption Standard initial position after 1.Na6
+ | fen:RBN1BRRQ/PPPPPPP/8/4n3/8/8/Nppppppp/brkbqr1n:
+ figcaption After 1.Nc6 Nf3 2.Nb4 Ne5 (covers d3 but not a2) 3.Nxa2#
h3 Source
projects / vchess.git / blobdiff