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[vchess.git] / views / rules / Upsidedown / en.pug

diff --git a/views/rules/Upsidedown/en.pug b/views/rules/Upsidedown/en.pug
index 695cbe4..8d4fa73 100644 (file)
--- a/views/rules/Upsidedown/en.pug
+++ b/views/rules/Upsidedown/en.pug
@@ -1,42 +1,32 @@
 p.boxed
        | Pawns start on the 7th rank. Move a knight to promote them.
 
 p.boxed
        | Pawns start on the 7th rank. Move a knight to promote them.
 

-Diagram: ... threatens Nc5-Nd3# and allow 2.b8=Q
+h3 Divergences

 
 

-figure.diagram-container
-       .diagram
-               | fen::
-       figcaption Standard initial position after 1.Na6
-
-h3 Specifications
-
-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.
 
 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.
 
        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.
 
 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.
        This allows to move free out of potential check from the very beginning.

-       Here is an example:

 
 

-// TODO: diagram
+p.
+       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
 figure.diagram-container
        .diagram

-               | fen:r7/2n5/1q6/5k2/8/8/K7/8:
-       figcaption.
-               The king cannot take on a8 because it's guarded by the knight: it's checkmate
+               | 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
 
 
 h3 Source