#5 Modified Betza Notation - modifier for spacious piece?

[Jerome Zago]

Context:
http://www.chessvariants.com/piececlopedia.dir/spacious-pieces.html. Note that they kind of assume a rectangular board.

Since the full alphabet is already used except q, I propose qs or _s.

Happy new year!

[Gregor Cramer]

I cannot see a real usage for this modifier. See variant "Spacious Torus Chess" on page Chess Variants. Here a board rule "spacious" will be used. Do you know a chess variant where only some pieces are spacious, and some not? And note that a spacious piece (here a King) can be expressed in the following way:

K=K-!mK

For me it is unclear how a spacious pawn is working, the referred page Chess Variants is not handling the pawn (moving forward like s Wazir, but capturing like a forward Ferz). Do you know the rule for pawns? Also the rule for knights is not 100% clear, is it

N=N-!mN

?

[Jerome Zago]

Hello,

AFAIK there are no published chess variants where some pieces are spacious and others are not. Actually I was thinking of using 1 or 2 spacious pieces for some random shogi setups described in https://github.com/agt-the-walker/shogi-utils -> Preamble. Indeed replacing a shogi knight by the FIDE knight (from Okisaki shogi) in the starting position of standard shogi might be too big a change, so it occurred to me that it could be replaced by the (less powerful) spacious FIDE knight instead. Other pieces would be non-spacious though.

Let's place a white spacious king on e2 on a 8x8 board with eight adjacent empty squares (not controlled by enemy pieces), I assume that K=K-!mK means that it can only go to e3 if e4 is empty (though this square might be controlled by enemy pieces), to f3 if g4 is empty, and so on. However it should also be able to go to d1 if c8 is empty, e1 if e8 is empty and f1 if g8 is empty, due to the concept of wraparound squares.

Let's place a white spacious FIDE pawn on e2 on a 8x8 board. e3 is empty and both d3 and f3 are occupied by enemy pieces. If I understood Betza's page correctly, this pawn can move to e3 only if e4 is empty, to e4 only if both e4 (obviously) and e5 are empty. It could capture d3 only if c4 is empty, and f3 only if g4 is empty. If the pawn were on e7 instead, it could only move to e8 (and promote) if e1 was empty.

Finally let's place a white spacious FIDE knight on g1 on a 8x8 board. e2 is empty, f3 is occupied by a friendly piece, and h3 is empty. Then this knight can go to e2 only if c3 is empty, and can go to h3 only if a5 (wraparound square) is empty.

What I like about the "spacious" modifier is that it can affect both leapers and riders. OTOH, the "halfling" modifier, while still very interesting, can only affect riders.

[Gregor Cramer]

I think that the definition of spacious pieces should belong to the board rules. So I have extended the rule torus, in your case you will use:

royal torus=spacious{N}

In this case only the Knight is a spacious piece, and only the Knight is wrapping around.

[Jerome Zago]

If I understood the following sentences correctly in http://www.chessvariants.com/piececlopedia.dir/spacious-pieces.html, a spacious piece doesn't mean that it wraps:

For example, if a Spacious Rook wants to move from e2 to e8, the wraparound square is e1 -- going out the top of the board and coming in the bottom -- and so the move (or capture) is legal if e1 is empty. Notice that the Spacious Rook cannot move through e8 to e1, instead it merely examines e1 when deciding if it can go to e8.

In other words, the legal moves of a spacious piece in a given position (with a given board) are either identical or are a subset of the legal moves of the non-spacious version.

For instance, my white spacious FIDE knight on g1 on a normal 8x8 board cannot go to a2 or h7, even if c3 and a5 are empty. So we can have one of:

• normal pieces on a normal board
• spacious pieces on a normal board
• a combination of normal pieces on a normal board
• normal pieces on a torus board
• spacious pieces on a torus board
• a combination of normal pieces and spacious pieces on a torus board

[Jerome Zago]

Of course, "a combination of normal pieces on a normal board" should be read as "a combination of normal pieces and spacious pieces on a normal board".

[Gregor Cramer]

Thanks for the clarification. I think that the best solution for your request is an enhancement of modifier "o". So I have done this, look at page Modified Betza Notation. If doubled ("oo") then it will wrap like a torus. So a definition of a spacious Knight is:

N=N-!mooN