Author: Robert Hyatt
Date: 05:17:27 11/10/97
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On November 09, 1997 at 21:50:43, Howard Exner wrote: >About a year ago someone posted a nice win of Crafty >against Genius 3 or 4 with the following opening moves: > >1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Bc4 > >None of my programs, MCPro 3.5, CM 4000 or Rebel 8 >have an opening book response to this. Just curious >how many programs have a book move response to this? > >My wild guess is very few programs released prior to >one year ago have a book response and that newly released programs >do. If I were a programmer I would include some book lines >for this unusual, yet quite sound move. > >How many programmers would admit honestly that they included >book lines as a result of seeing Crafty play this move? *every* programmer Jason talked to claimed they had added a line(s) for this opening. The ones that posted in r.g.c.c also said this, as well as those that talk with others that post there. Here's the story behind that opening, which I dubbed, "Ruy-Lopez, Crafty variation"... I added a mode to the book selection logic that would take the set of known book moves, and search *only* those moves and then play the best one. This search was significantly shorter than a "normal" search, to save time, but was hopefully deep enough to not play a book move that was an outright blunder. I played a game against Genius and the three moves after a6 in Crafty's book were the classical Bxc6 and Ba4, but there were three games with the Bc4 move as well. The search rejected Bxc6 as giving up the bishop pair, and it liked the bishop on c4 better than a4 because it didn't like moving it again after b5. I didn't particularly like Bc4, but forgot about it. In Jakarta, I told Tom to use this mode (book random 0) against any program he considered "strong". We didn't use it in every game because this would effectively disable any randomness and would allow between-round cooking if we weren't careful. What turned out to be quite good about this opening was that no one had any book line for it, and the few games in the book all had good, sound moves by black in it, so that most games went 20-25 moves in book, letting Crafty build up a *huge* time advantage, while the opponents were typically out of book at move 4, and got behind on time significantly. It turned out to be quite good. I first found out about it from Bruce, who had logged on to ICC to see if anyone had suggestions about a quick line to add. When he told me "why" I had a moment of panic, because I then remembered the Genius game but had forgotten about it. All turned out well, and most at Paris claimed to have a line in their book for this opening... :) It was *not* intended to be a trick, or general book cook, but it turned out to be cute... *very* cute... I believe the Crafty vs Virtual Chess game went 25+ moves in book for Crafty, but only 3 for Virtual, in Jakarta...
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