Monday, May 2, 2011

Chess960: Generating start position statistics

Note: For the moment Google has prevented me from making this Chess960 Google document publicly visible. Contact me if you want a copy.....

Here is a post of one way to calculate how many positions of particular configurations exist in the total set of Chess960 starting positions. I wanted to know how many SP's have bishops in their traditional locations. Here's what I did courtesy of Mark Week's Chess960 Position Generator:
  1. Used Mark's SP text list and published it as a Google document:
    Chess960 SP List As Google Doc
  2. Incredibly it looks like Google Docs text search facility doesn't allow searching with regular expressions although I'm sure at one point it did.
  3. So I downloaded the document into Open Office and did a regular expression search in it.
  4. Ctrl-F and make sure "regular expressions" is ticked under more options
  5. Typed in [a-z]{2}b..b[a-z]{2}
  6. Clicked on "Replace All" to show me how many replacements were made (60)
  7. Clicked "undo" with the search box still active and repeated for more searches
So there are 60 positions that have bishops on the c and f files. The question is what would have been the logical way to infer it?

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