Monday, April 4, 2011

Chess960: A Dice and

It's been described in quite a few places I think but I might as well do it again for my own benefit. I was down at the cafe the other day, people had chess set's but no dice! What better way to play Chess and have fun than with a dice down at the local cafe? If you go over to the wonderfully relaxing site you can throw a dice as many times as you like. How can a Chess960 position be generated out of that?
 = SP860

Step 1: Dark square bishop
The dice said '4' and so we put the bishop into the 4th dark square:
Step 2: Light square bishop
The dice said '1' and so we put the bishop into the 1st light square:
Step 3: The Queen
The dice said '6' and so we put the queen in the 6th available square:
Step 4: The first knight:
The dice said '3' and so we put a knight in the 3rd available square:

Step 5: The second knight
The dice said '5' but there are only four available squares. So we reject and roll again. This time the dice said '4' and so we put the knight into the 4th available square:

Step 6: The rooks and the king
We put the dice away because there are only three squares left. With those three squares you put the king in between two rooks:

Step 7: Mirror the white position for black

Now if you are sitting in a cafe with a chessboard, a friend a dice and a mobile phone, you can even write down the SP by typing RBKNRNBQ into Google. Google says it is SP860. If you don't have an internet connection then calculate the SP in your head using Mark Weeks clever technique:
The hardest part about this little exercise, is that you need some money to pay for the espresso. OK I'm kidding. The hardest part is working out the SP in your head!
Here's how to do it courtesy of Mark's blog:

Step 1: What are the sequence of K, R, N?
Answer: RKNRN

Step 2: Find the KRN sequence in the table:

Answer: 8x96 = 768

Step 3: Find the position of the queen in the table:
Qxxxxx 00
xQxxxx 16
xxQxxx 32
xxxQxx 48
xxxxQx 64
xxxxxQ 80

Answer: 5x16 = 80

Step 4: Find the position of the bishops in the table:
00 BBxxxxxx
01 BxxBxxxx
02 BxxxxBxx
03 BxxxxxxB

04 xBBxxxxx
05 xxBBxxxx
06 xxBxxBxx
07 xxBxxxxB
08 xBxxBxxx
09 xxxBBxxx
10 xxxxBBxx
11 xxxxBxxB
12 xBxxxxBx
13 xxxBxxBx
14 xxxxxBBx
15 xxxxxxBB
Answer: 12x1 = 12

Step 5: Add the answers
Answer: SP = 768 + 80 + 12 = 860!

Cinch. Anyway, what a great way to find the SP by general principals c'mon admit it. Note that the tables can be derived logically and thus done in your head while you are at the cafe! Probably best to calculate it after the game or you will probably loose by confusion.

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