28 March 2020

Epaulette Mate

Here's an interesting idea found on Chess.com in a forum thread titled Chess960 Fool's Mate Variation. In the following diagram it's checkmate after 1.e4 b5 2.Qxb5# .


SP921 RKRBBQNN

The thread eventually determines that there are two such RKR***** positions (plus two more *****RKR mirrors). Why two? The Queen must be on the f-file and a Bishop must be on the d-file, because a Knight on that file can block the Queen check. That leaves three squares still to be occupied. The other Bishop must be on the e- or g-file, leaving the last two squares for the Knights.

The thread doesn't discuss the related positions *RKR**Q* and **RKR**Q. In fact, these can't lead to the same mate, because the two Bishops must be next to the Rooks, which places them on the same color square.

All 960 start positions are subject to some sequence of moves -- similar to a 'helpmate' problem -- that leads to the shortest mate for that position. Which positions require the most moves?

21 March 2020

Problem Pieces

A few months ago, in 2019 Champions Showdown Live (October 2019), after linking to a number of videos from the 2019 Champions Showdown, St. Louis, I closed with a question:-
How am I ever going to find the time to watch all of this?

Today I decided to use this post to start the viewing, but first I stopped in to watch round four of the 2020 Candidates Tournament; Yekaterinburg (Russia). I hadn't been able to see the first three rounds and the fourth day was a rest day. Traditional chess is alive and well! The four games were so interesting that I spent most of my free time following the action. After three draws and another draw looming, I finally switched over to the video for a round from St. Louis:-

Streamed live on Sep 2, 2019; 2019 Champions Showdown | Chess 9LX: Day 1

Since chess is primarily a competitive activity, watching a game is more exciting when you don't know the outcome, but it's still interesting. The announcers -- Yasser Seirawan, Jennifer Shahade, and Maurice Ashley -- did a thoroughly professional job explaining the ebb and flow of the games. The chess960 opening is the most challenging phase to explain, so I paid particular attention to the experts during the early moves.


SP366 NRKRQBBN

The diagram shows the start position for the first two rounds, i.e. eight games. At 18:50 into the video GM Seirawan said,

When you look at a chess960 position for the first time, you identify which pieces are problem pieces. I would identify Nh1 and Bg1. Which Pawn is the most vulnerable? Most likely the a2 & a7 Pawns [since they] are the only ones that aren't protected. Those will be the Pawns that the players first begin to attack.

I would have identified Na1 and Nh1 as the problem pieces. In fact, any piece starting in the corner, except a Rook, presents a problem. As for the Bg1, it is set to attack Pa7, making it more of an asset than a problem. But I won't quibble with the GM; his methodology is what counts.

P.S. Can we call SP366 the Leap Year position?