Chessgames.com Start Position XREF

In last week's post, SP864, Reddit, Chessgames.com (April 2021), I wrote,

Chessgames.com: I [...] discovered that the book was structured as an introduction to chess960 from several angles. Unfortunately, it had a big problem. The start positions used Chessgames.com numbering which is non-standard.

I also said,

I've mentioned the Chessgames.com pitfall many times on this blog, but the problem needs a more permanent warning.

To make progress, I created a cross-reference (aka XREF) between standard start position (SP) numbers and Chessgames.com numbers. I uploaded the cross-reference to my own site as a new page:-

• Chessgames.com SP Converter (m-w.com/cfaa/chess960/c960chgm.htm)

I tested the cross-reference on a discrepancy documented in a previous post, Champions Showdown, St. Louis (September 2018), where I wrote,

I noticed one anomaly that I don't understand. The official site's 'Results' page noted the start positions and their numbers for each round, but the numbers don't correspond to the system that I'm familiar with. For example, it gives the first day using 'Position 598: NQBBRKRN'. I prepared the following table for this post, where the first column is the round number and the second column is the numeric start position:-

1: SP309 NQBBRKRN
[...]

Indeed, the chess960 standard number SP309 is the equivalent of the Chessgames.com non-standard number 598. Another unsuspecting soul had fallen into the Chessgames.com trap.

My cross-reference is crude and lacks the HTML tags that make a proper web page. I'll improve it as soon as I can and, at the same time, integrate it into my other chess960 resources.

SP864, Reddit, Chessgames.com

In the few weeks since since my previous post, I've received three noteworthy messages worthy of separate posts. I'll list the messages here according to the order in which I received them.

SP864: The first message was a comment by Andrey D. to my most recent post, TCEC C960 FRC3, (March 2021):-

You might be interested in knowing the solution for Black in a particularly difficult SP we once discussed.

In fact, there are two 'particularly difficult' SPs that are related by switching two pieces. I'll reference them via my 'Database of SPs'. The first is:-

• SP864 - BBQRKRNN

The second is:-

• SP868 - QBBRKRNN
• A Difficult SP Revisited (May 2019)

I include a second link for SP868 because I haven't updated the database since I wrote the post two years ago. At the end of this post, I've attached a substantial portion of Andrey D.'s comment in PGN format. It's an important discovery.

Reddit: The second message was an email. My email address can be found on my profile linked in the top right of every page in this blog ('View my complete profile'). The message said,

Maybe you could share some of your articles on /r/chess960, which is pretty much dead.

I replied,

Please feel free to link any of my blog posts on Reddit.

If I could find the time, I would be more proactive than that. The Reddit topic is at chess960 related topics (reddit.com). The world needs a public forum to discuss chess960/FRC.

Chessgames.com: The third message was also an email. It had two PDF attachments that were introduced with:-

It is a pleasure for me to have carried out this humble book with the 960 initial positions, obtained from the page chessgames.com, making screenshots of the 960 positions and diagramming them in the "DIAGTRANSFER" software and placing them in my book. It is in Spanish because I am from Argentina.

I used Google Translate to understand the Spanish and discovered that the book was structured as an introduction to chess960 from several angles. Unfortunately, it had a big problem. The start positions used Chessgames.com numbering which is non-standard. I last saw this a year ago in a post about the '2019 Champions Showdown', Spectating Chess960 (April 2020):-

Day 4 started with a curiosity. The first start position (SP784 BBRQKNRN) was the twin of the position on Day 3 (SP175 NRNKQRBB). [...] NB: After choosing the Day 4 position, TD Tony Rich called it 'SP779'. He was using the Chessgames.com Random Position Generator, which does not follow the standard numbering.

I've mentioned the Chessgames.com pitfall many times on this blog, but the problem needs a more permanent warning. A good place to mention it would be my page Chess960 Start Positions (m-w.com). The page appears in the results for various searches and gets a fair amount of traffic. A table converting between the two numbering systems might also be useful.

***

Some GM analysis:-

[Event "SP864"]
[Site "?"]
[Date "????.??.??"]
[Round "?"]
[White "W"]
[Black "B"]
[Result "*"]
[Annotator "Andrey D."]
[SetUp "1"]
[PlyCount "0"]
[FEN "bbqrkrnn/pppppppp/8/8/8/8/PPPPPPPP/BBQRKRNN w - - 0 1"]

1.Ng3 c5
  ( 1...f6 )
  ( 1...Nf6 )
  ( 1...g6 )
2.Nh5 f6 3.Nxg7+ Kf7 4.Nh5 Ng6 {This counter-intuitive gambit is in fact very logical upon a closer look; note that White's only piece [pawns included] that has moved so far is his h5-knight which will be forced to retreat soon. Meanwhile Black has already played ...c5 and ...Ng6, and is now intending ...d5 followed by ...Qg4! and ...Nf4!, gaining further tempi. The semi-open g-file can also be used rather by Black than by White [especially if the latter castles h-side].} 5.Nf3 d5 6.b4 b6 7.bxc5 d4
  ( {Morphy-style! However simple} 7...bxc5 {was also fine for Black.} )
8.Qa3
  ( 8.Bxd4 Rxd4 9.Nxd4 Qxc5 {and one of White's knights will be lost} )
  ( 8.cxb6 {ignoring development altogether} 8...Bxf3 9.gxf3 Qh3 {with a number of threats for the sacrificed material.} )
8...Qg4 9.Ng3 Nf4 {the roles are now reversed and it's White who has to play Rg1, because if 10.0-0? then 10...d3! 11.cxd3 Nxe2+ 12.Nxe2 Bxf3} 10.Rg1 bxc5 11.Qxc5 e5 {And Black, who has a very strong initiative for two pawns, went on to win in a long and absolutely crazy fight!} *

I wouldn't be surprised to find a similar line for SP868.