Chess960 1-2-3, April 2015

I updated my Index to Blog Posts, last seen in A New Page, a TOC, and a Logo (June 2014). Most of the new links were in sections 2A and 3D. I haven't done as much with the page as I had hoped, mainly because of a lack of ideas. Perhaps something compelling will come to mind.

Illegal for Chess, Legal for Chess960

A few weeks ago, in CHESSIS2C960 Visually, I mentioned,

Certain problems/studies that are illegal in chess might be legal in chess960, but I can't give any specific examples.

While writing that post I didn't have time to hunt for examples, but they aren't too hard to discover. In Chess glossary for Freshman Seminar: Chess and Mathematics, I found

Legal position (n.): a position that can be reached from the initial array by game consisting entirely of legal moves, however bizarre. Conventionally every chess problem should have a legal position. Naturally then, an illegal position is a position that cannot be reached by a legal game. For instance, a position in which one side has more than 8 pawns, or has both White and Black Kings in check, is illegal (why?). So is any position with a White Bishop on a1 and White pawn on b2 (why?), such as the following mutual Zugzwang (q.v.), which Lewis Stiller discovered in the course of an exhaustive computer search: White Kg6, Bh1, Pg2; Black Kg4, Pg3.

The given position is shown in the following diagram.

Mutual Zugzwang

[FEN "8/8/6K1/8/6k1/6p1/6P1/7B w - - 0 1"]

The tablebase used in Shredder Computer Chess - Endgame Database accepts the position as valid and gives WTM 'Draw' and BTM 'Lose in 20'.

CHESSIS2C960 Chess.com

In the previous post I tried to present Chess is to chess960 [CHESSIS2C960] Visually. At the same time I asked the collective brainpower at Chess.com,

I'm looking for chess analogies to explain chess960: 'Chess is to chess960 as ... is to ...' Any suggestions? • Chess960 Analogies

It was the right forum to ask. Eliminating a handful of examples that I threw in myself, some worthy suggestions were:-

• as black & white TV is to color TV
• as V2 is to V3
• as raw spaghetti is to cooked spaghetti
• as blind obedience is to self reliance
• as Nascar racing is to F1
• as F1 is to Nascar racing

Midway through the discussion, I realized that a better formulation might have been 'Chess openings are to chess960 openings as ... is to ...'. Thanks to the racing analogies another angle occurred to me while I was preparing this post.

Chess *castling* is to chess960 castling as an automatic transmission is to a stick shift.

Why? Because in traditional chess the choice of 'where' to castle is usually obvious (and often conventional) although 'when' is sometimes tricky. In many chess960 openings one of the hardest early decisions is where and when to castle.

Which of the analogies do I like best? I'm not sure, but the one I understand the least is about spaghetti.