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M Winther wrote on Thu, Apr 27, 2006 07:52 AM UTC:
Reinhard, the Mammoth *jumps* two squares. This significantly increases its
strength and makes it such an interesting and valuable piece on the big
board.

The problem of knight and bishop also has to do with the fact that their
values are so flexible. A centrally positioned knight in the middlegame,
on a square which cannot be threathened by a pawn, acquires the value of a
rook. In the endgame, when pawns are located only at one wing, the knight
is often more valuable than the bishop, sometimes winning the game,
despite equal material. However, the cooperation of two bishops can
increase the value of a bishop considerably. 

The derivation of piece value seems to be a complicated science. If we use
Taylor's notion that the value of a chess piece is proportional to its
ability to safely check an enemy king on another otherwise vacant board,
then the Mammoth is less valuable than a rook, since the rook can give
check from many more squares. It seems that this piece has great strengths
and great weaknesses.

Mats

Christine Bagley-Jones wrote on Thu, Apr 27, 2006 08:00 AM UTC:
then you prosume wrong, he he, it is a leaper +
i made the comment 2 down, forgot to enter name, i was just saying that i
thought the mammoth has to be stronger than the rook, it is alfil +
dabbaba + wazir + fers, that is a heavy piece, i know just the alfil +
king moves is a strong piece, the mammoth is a killer at short range, all
over the pieces like oprah on pork chop nite :))

Reinhard Scharnagl wrote on Thu, Apr 27, 2006 08:05 AM UTC:
Mats, of course a jumping Mammoth is stronger. My 10x8 scheme gives a
value of 6.7778 to it then, which is nearly identical to an Archbishop's
value of 6.8580. Regards, Reinhard.

M Winther wrote on Thu, Apr 27, 2006 09:09 AM UTC:
Are you sure that you got this right? The Mammoth (Mastodon) *jumps*
 one or two steps diagonally or orthogonally. It cannot be as valuable
 as 6.8. Those evaluation systems don't work because they don't take into 
account how pieces *relate* to each other. Nor does the simple counting of 
squares work, i.e., its factual power, because it doesn't take into account 
that the Mammoth has to flee to every threat and cannot strike back. For 
instance, if a rook is threatened by a queen it can strike back on the 
orthogonals. The Archbishop can strike back against a threatening bishop, 
queen, or knight, but a Mammoth must generally back off before any threat. 
I argue that the Archbishop must be clearly more valuable than the 
Mammoth.

The Mammoth seems ideal for testing the reliability of evaluation systems.

Reinhard Scharnagl wrote on Thu, Apr 27, 2006 09:33 AM UTC:
Hi Mats, yes, I handled the Mammoth as a fully jumping piece. Your
arguments whether the piece is not save towards distant threats is a
TACTICAL argument, which has nothing to do in average piece value
considerations. Be aware, that a Mammoth also has the chance to escape
such threats by his numerous move possibilities. And - as already earlier
stated - real exchanges would have to consider the actual positional
implications of all pieces within the actual board situation.

P.S.: I should mention again, that my scheme is calculating AVERAGE piece
values, which have to be completed by positional detail evaluations when
evaluating real board positions.

P.P.S.: See also at http://www.chessbox.de/Compu/schachveri1_e.html

M Winther wrote on Thu, Apr 27, 2006 11:33 AM UTC:
I have investigated the theoretical endgame properties of the Mammoth and
it proved to be significantly stronger than the Rook in this area.

(1) M + K  vs. Q + K  = draw
(2) M + K  vs. R + K  = draw
(3) M + K  vs. B + K  = win
(4) M + K  vs. N + K  = win

Comparatively, a Rook + King cannot win against neither Bishop nor Knight,
in the general case. This implies that the Mammoth is stronger in
theoretical endgames. Moreover, Rook + King generally loses against 
Queen + King, but the Mammoth draws against Queen.

Also, in a theoretical endgame, a Mammoth is well suited for escorting a
passed pawn to the promotion square. Bishop, Knight, or Rook, cannot
achieve this.

So it is stronger than a Rook. I contend that it compares to Rook + Pawn,
i.e. 6. But I refuse to believe that it's as strong as an Archbishop (6.8).

David Paulowich wrote on Thu, Apr 27, 2006 11:43 AM UTC:
I still believe in the power of short range leapers. The Mammoth should be equal to an Archbishop/Cardinal on the 8x8 board, and to a pair of Bishops on the 10x10 board [Edit: also equal to Rook + Pawn]. I just read the comment below by Mats Winther. Simple 'pawnless endgames' are a good test of piece strength.

For an index to Ralph Betza's work, see About the Values of Chess Pieces -- Contents. His early attempts at STANDARD values (including Ferz, Alfil, and King/Commoner) can be found here.


Reinhard Scharnagl wrote on Thu, Apr 27, 2006 12:01 PM UTC:
Hi Mats, your arguments remind me at those of Ed Trice. This is also true
for basing piece values on 'save' king threats. But I have to insist,
that tactical considerations have nothing to contribute to average piece
value calculations. There are of course board situations, where a Pawn
could capture a Queen, but that is completely irrelevant for those
figures. In a similar understanding end-game considerations are highly
influenced from tactics, thus conclusions basing on table bases are merely
of partial value for fixing average piece values as needed during the whole
game before. 

P.S.: using SMIRF's 10x8 values a Mammoth or an Archbishop both are about
equal to a Rook's value + one Pawn unit or equal to two Bishops.

M Winther wrote on Thu, Apr 27, 2006 04:25 PM UTC:
It's not only a matter of technique to study theoretical endgames. Although considerations of theoretical endgames are of tactical nature they are important also from a strategical perspective because the capabilities of the pieces create certain motives that are quite important, and sometimes surface already in opening and middlegame. An obvious example is the sacrifice of the light piece on the opponent's remaining pawn(s). Although the opponent has a Bishop or Knight against a lonely King, this is not enough for win. Such factors affect the whole game, from the beginning. The fact that the Rook cannot win against light piece in the ending, is underlying the common motif of the positional sacrifice of a Rook against Knight or Bishop in the middlegame. Tigran Petrosian often used this idea. These sacrifices bring no tactical advantage, but are strictly positional.

(I have now improved the opening play in my Mastodon Chess (8x10))

M Winther wrote on Thu, Apr 27, 2006 06:01 PM UTC:
I made a test where I put an Archbishop + King versus Mammoth + King on 
an otherwise empty board in Zillions. On an 8x8 board Zillions evaluates
Archbishop and Mammoth as equal. But on an 8x10 board Zillions evaluates
the Archbishop as significantly stronger than the Mammoth (so that the
smiley looks unhappy when making the Mammoth move). On a 10x10 board 
the difference increases yet more in the Archbishop's favour, but not that
much. So Zillions thinks that the Mammoth has about the value of an
Archbishop on an *empty* 8x8 board, but this evaluation changes when the
board is bigger. This corroborates what has been said recently, although
I'm unable to interpret Zillions' numbers.

Sam Trenholme wrote on Sun, May 7, 2006 07:10 AM UTC:
I'm curious. Why a RMBNQKNBMR opening setup instead of a RMNBQKBNMR setup? I like having the knights and bishops in the same places that they are relative to the king in FIDE Chess; swapping the bishops and knights like that just seems to make the pawns get in the way of the bishops.

As an aside, another of Greenwood's variant with this piece is Tamer Spiel (a 2002 variant) where it is called the 'Lion'.

- Sam


M Winther wrote on Sun, May 7, 2006 01:59 PM UTC:
Sam, for this game I investigated many initial positions, even non-mirrored.
This was the only one I found that was good, I think. Why I didn't choose
the 'natural' positions of bishops and knights had to do with the fact
(if I recollect correctly) that the enemy mastodon would lose its natural
development square on b3, b6, i3, i6. Also, the flank pawn would also be
initially threathened by the bishop, which would be a hindrance to
castling. It's possible that my 10x10 version of MastodonChess is better, at 
least more strategical. Thank you for the information on TamerSpiel. 

--Mats

Sam Trenholme wrote on Mon, May 8, 2006 04:19 AM UTC:
I think those are good points. Then again, the A and J pawns on an 8x10 setup are poisoned pawns for the bishop; if the bishop takes, say j2, the move pawn to I3 traps the bishop. As for hindering b3/I3 development, since the mammoths are about as valuable as archbishops, they are pieces which will probably not be developed until the later mid-game, when the bishops are no longer on their home squares. Also, the high level of power and relatively slow movement of the mammoth makes them more suited as defensive rather than offensive pieces.

I think the solution to the castling problem is to use the castling rules that grotesque chess has.

- Sam


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