Tuesday, March 20, 2012

Chess960: The more the better? part 2

Lately I've been experimenting with "Asymmetric Chess960" which is also called "Chess960 squared" (see comment below) or "Double Chess960". It is where the start position is a unique SP for each color.

One of almost one million possible Asymmetric Chess960 starts

Now you might think that this is crazy to do. But after testing quite a few positions against a computer, the rough start position evaluation range that the computer gives is kinda unexpected:

Approximate evaluation range according to Rybka 4 960 on average across many of these asymmetric positions:
White max eval roughly +0.45 at best
White min eval roughly  -0.25 at worst

Now that last result is the amazing part. In asymmetric Chess960 you get some start positions where black has an advantage at the start! It produces the bizarre situation where white is sitting there thinking about playing the first move, and they are already in a quandry. This could be because white's queen is not so well placed relative to blacks for example.

So what about the idea of Basque asymmetric chess to make asymmetric chess completely fair for both players?

Taking a leap from Mark Weeks blog on simultaneous chess, I thought I'd give a special case of  asymmetric Chess960 games a go on a computer. As Mark says, the advantage of the Basque system is that if players play the same start as both black and white simultaneously, then any imbalance from white starting first is removed (so long as you score the result properly).

A Simultaneous Asymmetric-Chess960 game using Winboard

As you can see, the same  asymmetric Chess960 position is played as both white and black simultaneously. I tried this out and it turns out to be a lot of fun and is by no means overwhelming so long as you make the time control long enough! It actually refreshes single board play, because the multitasking on two boards really teaches you how to organize the way that you think, which is useful for single board play.

Here is the only Chess software that I know of on the planet right now, that is capable of such a feat:
  1. Winboard 4.60 and Aquarium 3.11 are the only GUI's that can cope with Chess960 castling uniquely for each color on the same board, while simultaneously being able to run two boards side by side on the same screen.
  2. Arena 3.0 and Fritz 12 cannot handle it.
  3. The only high quality chess engine that I know of that is commercially available that can handle  asymmetric Chess960 start positions is Rybka 4 960. This is because the author must have written the engine to generate the correct bitboards for this unique start concept. This was extra work for him but much appreciated.
  4. Critter 960 and Fritz 960 do not understand  asymmetric starts
So, on a rainy Sunday afternoon, fire up two instances of Winboard 4.6 of Aquarium 3.11 with the UCI engine Rybka 4 Chess960 running on each. Paste in a unique asymmetric Chess960 FEN into Winboard and have fun! Just remember to keep an eye out on two chess clocks not just one and try not to get distracted when the computer plays a move on the other board.

So, enjoy a bit of Chess960 any way you like it.

PS) I've since learned that Houdini 2c is also capable of asymmetric Chess960

PSS) I'm in the middle of writing some software that rejects the top end of white's advantage in asymmetric Chess960. This theoretically leaves the start evaluation in the range of +0.25 to -0.25 for many hundreds of thousands of asymmetric Chess960 starts.

PSSS) Having experimented with asymmetric Chess960 some more, it really is enjoyable. This is because both sides have more flexibility and resources, because they are less restrained by the problem of symmetry stifling the opening sequence. This actually tends to make asymmetric chess a bit easier than straight Chess960 I think.

PSSSS) If the top end of white's favourable asymmetric Chess960 starts are not removed, the main theme that gives white a big advantage, is when white has two of the major pieces on one side of the board and black does not. This allows white to push the pawns out on the side where the major pieces are and gives white a lot of space. However what I am finding is that black has a lot of resources, surprising number of ways to counter and sometimes it is white that is on the defensive. That said, the one million possible asymmetric Chess960 starts probably does contain a few problem starts, and that's why they need to be pruned. But there are not as many as you would think!

Wednesday, March 14, 2012

Chess960: The Great King's Pawns Opening Research Project part 2

Just thought I'd run this finding past anyone out there who is interested in Chess960 research. There are not many of us, but those of us who are should stick together and talk!

Here is part two of the great king's pawn research project. You know the old traditional move 1. e4.

Part one is here

Here is an amazing contrast between two adjacent SP's that switch two minor pieces. In one SP, the kings pawn opening is totally benign and quiet, while in the other it is dynamic and exciting. The two SP's are SP444 and SP445:

SP444 is draw?

SP445 is alive!

Here are some points on SP444 and SP445 that you might find interesting. You really have to play with them and experiment with them so see how totally different these SP's are in terms of their degree of volatility. 
  1. The only difference between them is that Nb1 and Bd1 are swapped
  2. The really standout feature is that in SP445, the Nd1 that stays the same in both SP's suddenly has a really surprising developing move Nd3!? that actually is good sitting out in front of the d2 pawn because none of the other pieces are blocked and white still has powerful pawn initiatives even without the d-pawn taking part. There is an excellent parallel with this developing move and Aronian's discovery of Nd3 in SP941. In SP445 there is an underlying theme of a pawn gambit line with e4/Nd3/f4!?
  3. In SP444 however, Nd3 does not work nearly as well simply because the b1 bishop is blocked which is not the case in SP445.
  4. Because of the surprisingly good developing move of Nd3 in SP445, white has a whole bunch of extra choices that are all good. They can push the g-side pawns and castle c-side for example.
  5. For some strange reason that I do not understand fully, in SP444, almost all opening lines are totally evaluated at less than 0.1 going to huge depths of over 16 ply in many many variations. However in SP445, with the simple switch of the knight and bishop, the game is much sharper earlier on.
  6. SP444 is a draw question, should not underestimate that it is still a very interesting SP. If you play through it, you find that black has perfect counter play for almost everything white does, but that all of the sharpness in the SP is not in tactics, but in the very deep positions that emerge later on, in the late midgame.
This contrast between SP444 is a draw? and SP445 is alive! is an excellent example of how different SP's distribute the sharpness of tactics verses position over time. SP444 only becomes sharp very late in the game, while SP445 is sharper earlier.

Enjoy researching Chess960 (for the very few of us that are out there)