Redundant knight

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hgm
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Re: Redundant knight

Post by hgm » Sat Jun 21, 2014 11:52 am

Lyudmil Tsvetkov wrote:
hgm wrote: Engine analysis has nothing to do with reality.
:D :)
I think this sums it up very nicely.
Indeed. But it seems you have difficulty grasping this fundamental truth.

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Re: Redundant knight

Post by Lyudmil Tsvetkov » Sat Jun 21, 2014 11:59 am

[d]4rbk1/1pp2ppp/p1b2n2/8/8/P1N2N1P/1P3PP1/R2R2K1 w - - 0 1
Another typical redundancy-related position. Pair of bishops + pawn are usually completely equal to R+N, but here there are specificities in terms of available redundancies for both sides.

Black does not have even a single redundancy, even partial, in a set of 4 pieces, while white has 2 redundant rook and knight pairs. This would give white an additional advantage of some 30cps, and therefore I think objectively black is better here.

[d]6k1/1pp1bpp1/p1b4p/8/8/P1N4P/1P3PP1/3R2K1 w - - 0 1
Once we remove the redundant pairs, the position is completely equal.

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Re: Redundant bishop

Post by Lyudmil Tsvetkov » Sat Jun 21, 2014 12:10 pm

BBauer wrote:[D]8/8/3k4/8/3B4/4B3/3K1B2/8 w - - 0 1

What penalty would you give for three redundand bishops?
Hope this shows the nonsense.

Kind regards
Bernhard
Very big one, you see black can not get mated.

With more material on the board,a same-coloured bishop would deserve a penalty maybe roughly equal to 1/3 of its value (so that the engine knows it should not promote such bishops), if such a bishop plus a same-colour counterpart are the only available pawn and non pawn material on the board, of course you could cancel the full bishop value altogether.

Evidence has showed that similar underpromotions happen even in real games, so a penalty would not be a stupid thing at all.

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Re: Redundant knight

Post by hgm » Sat Jun 21, 2014 12:11 pm

Lyudmil Tsvetkov wrote:So why 2 white knights, 6 full pawns material advantage, are unable to win against a lone king? There is no pawn span there, no major pieces to excuse that knights get weaker with less pawns, but rooks stronger, absolutely nothing. Why is white not able to win this?

Well, the answer is very simple, because the knights are redundant, even more so in the absence of any other pieces.
Mating potential is a very specific property, which has only very little effect on general piece values. The Spartan Captain (moving 1 and jumping 2 squares orthogonally) has mating potential, yet it is worth less than a Knight.

Lack of mating potential does deserve a penalty, and in fact an extremely high penalty, once it has materialized. Presence of other pieces, and in particular Pawns, very quickly soften it, however. Implementing it as a general penalty for a Knight pair is thus a bad mistake. It should be highly dependent on the number of remaining Pawns. With few Pawns, having no mating potential in the non-Pawn material seriously jeopardizes your current mating potential. All this is well known, and top engines are fully aware of it. They implement it as a Pawn-dependent term, not as a general redundancy penalty.

Having two equal pieces has indeed a larger chance of one of them not meeting the requirements to complete a mate. But it is by no means the only case. A Knight plus a Zebra ((2,3) leaper) have no mating potential. Yet there is no redundancy between them. So how do you explain that?

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Re: Redundant bishop

Post by hgm » Sat Jun 21, 2014 12:16 pm

Lyudmil Tsvetkov wrote:With more material on the board,a same-coloured bishop would deserve a penalty maybe roughly equal to 1/3 of its value
This, in fact, has also already been proving wrong. Two equal Bishops have been shown to be simply worth twice the value of a single Bishop. So there is no B-pair bonus in that case, but no additional penalty. Like Bishop versus two Knights is almost an exact wash.

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Re: Redundant knight

Post by Lyudmil Tsvetkov » Sat Jun 21, 2014 12:58 pm

Probably one last of the series.

[d]2r3k1/1p2bpp1/p1b2n1p/8/8/3Q3P/6P1/R4RK1 w - - 0 1
Nominally, it is R for 3 pawns, so white should lead in terms of material by 150cps, but when you add the bishop pair, the 2 black passers, it comes down to some 60-70cps white edge. Add to this the penalty and half for the redundant white majors, and you decrease the white edge to some 40cps. As the white pawns must shelter the king, they can not be used for storming and in this way it is not clear how white is going to break through.

So that every single element counts, objectively.

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Re: Redundant knight

Post by arjuntemurnikar » Sat Jun 21, 2014 2:23 pm

hgm wrote:
Indeed. But it seems you have difficulty grasping this fundamental truth.
Why do you argue with a wall? No matter how reasonably you try to explain things to him, he will just hit back with the same unreasonable argument. He is always like this.

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