Letter #11 - 2009
Something of interest
Date: 3/02/2009 7:02:27 PM EDT
I found the following information on a web blog which I believe is very informative and interesting. Hope you guys like it and put it on your nice site.
Thank you for this article that we have found very good and we believe our Chess viewers will enjoy it:
“Here is how I found what I believe to be the largest Chess game
possible. Remember the 50th move rule, which states that every
50 moves, a Pawn move or a capture must be made. This ensures
that there is a finite number of possible moves. We will assume
that black or white can move on the 50th move to make things
Four of black's Pawns will capture four white pieces (not white
Pawns), and four of white's Pawns will capture four black
pieces. This enables 16 Pawns to move 6 spaces each, and
16*6=96. How many pieces are left to be captured?: 32 pieces -8
captured pieces=24. Actually, 22 pieces will be captured because
the two Kings can't be captured. BUT, when the two Kings are
left, they will move 50 additional moves until the game is a
draw. So that is like "capturing" a King. 24 pieces -1 King = 23
Multiply 50 by the sum of 96 and 23, because 50 moves ensue
before a capture or Pawn move, and you get 119*50 which equals
5950. This is close to the number 5949, which one website
(chess-poster.com) has posted. This is not correct because we
must now calculate how many times the captures / Pawn moves
SWITCH from black to white, and subtract that number from 5950.
Here's how: at first, 2 black Pawns capture 2 white Knights.
Now, black can move 4 pieces (2 Knights, a Rook, and a Bishop
for example) onto squares where white Pawns can capture them. In
the meantime, white can move his Rooks back and forth while
black moves his Knights around or develops his pieces through
the openings that the black Pawns created.
This proves that both sides can move around while waiting for
the 50th move. When white captures the black pieces, he moves on
the 49th move, so we subtract 1 from 5950 to get 5949. After
white captures 4 black pieces, the white Pawns can not all
promote because two black Pawns still need to capture white's
So, we need to make another switch. 49 moves after white's Pawn
moved, black must make a Pawn capture to get all of his Pawns
ready to promote. 5949-1=5948. With black moving on every 50th
move, he can promote all of his Pawns. He can't capture all of
white's Pawns and pieces because white still has to promote all
of his Pawns. So white must move; we need another switch.
Now, with white making a capture/Pawn move every 50 moves, he
can now capture all of black's pieces except the black King.
Note: white can position his Knights (Pawns can promote into
Knights) in order to shield the white Rooks, Bishops, and
Queen(s) from checkmating the black King while he is alone. We
need one more switch; the black King must now capture all of the
white pieces! 5947-1=5946.
After there are two Kings on the board, they move 50 more times
until the game is a draw. As you can see, most of the time,
there are 50 move intervals between Pawn moves/captures, whether
they were made by white or black. There are only four 49 move
intervals between Pawn moves/captures, as I just showed, which
is why I subtracted 4 from 5950. I simulated part of this game
to explain below (only around 20 moves, not 5000!).
Please comment if you disagree or have an alternate solution
that gives more moves. I would like to know why someone
calculated 5949 moves. That is only 3 apart from what I
calculated, so I'm sure our solutions are similar. Note that
this may not be the best solution; of all the solutions I could
think of, this was the largest number of moves.”
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