Why is this position evaluated so?

Technical questions regarding Openings, Middlegames, Endings etc.
Roger de Coverly
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Re: Why is this position evaluated so?

Post by Roger de Coverly » Tue May 09, 2017 10:08 am

soheil_hooshdaran wrote: What is wrong with 1..Na5
Some calculation is needed as the obvious sequence 2. Nxa5 Qxa5 3. Bxb7 loses a piece. You have to flick in 2. .. Bxe4. But with two minor pieces being exchanged, the position is changing.

Otherwise .. Na5 looks sensible to evict the well placed Knight from c4.

soheil_hooshdaran
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Re: Why is this position evaluated so?

Post by soheil_hooshdaran » Tue May 09, 2017 11:40 am

Am IM friend of mine played ...Na5 and was crushed by another IM friend of mine.

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IM Jack Rudd
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Re: Why is this position evaluated so?

Post by IM Jack Rudd » Tue May 09, 2017 12:10 pm

soheil_hooshdaran wrote:Am IM friend of mine played ...Na5 and was crushed by another IM friend of mine.
That doesn't necessarily prove ...Na5 is at fault. Black may already be in a tricky situation.

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Re: Why is this position evaluated so?

Post by soheil_hooshdaran » Tue May 09, 2017 1:01 pm

But I analyzed it with Stockfish, Jack

Roger de Coverly
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Re: Why is this position evaluated so?

Post by Roger de Coverly » Tue May 09, 2017 1:09 pm

soheil_hooshdaran wrote:But I analyzed it with Stockfish
There are positions which an engine will evaluate as equal because there are many decent moves available. There are also positions which are evaluated as equal because it can see its way through a forest of complex variations.

What does it suggest as an alternative to .. Na5?

soheil_hooshdaran
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Re: Why is this position evaluated so?

Post by soheil_hooshdaran » Tue May 09, 2017 2:05 pm

...Bc5

soheil_hooshdaran
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Re: Why is this position evaluated so?

Post by soheil_hooshdaran » Wed May 10, 2017 7:36 am

Why does White win

?

Roger de Coverly
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Re: Why is this position evaluated so?

Post by Roger de Coverly » Wed May 10, 2017 8:43 am

soheil_hooshdaran wrote:Why does White win
Presumably there's a long line you have to calculate where playing b6 would force the win of the Bishop on d8, the King defends the pawn on d7 and the Bishop on c8 is in time to stop either of the g and h pawns becoming queens. Kd5 looks to be the starting move, as if Kf5, then Kd6 can stop the b pawn whilst the Bishop on d8 holds the g5 pawn.

(edit) Another thought on this, perhaps there's a Zugswang idea as well. So get the pawn to advance from g5 to g4, then eat up the g and h pawns with the King. Again a long variation (/edit)

John McKenna
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Re: Why is this position evaluated so?

Post by John McKenna » Wed May 10, 2017 12:43 pm

As is usual with our Persian pal there's more to it than meets the eye - he doesn't say "White to play and win" and if not then 1... h4 might hold the draw?
To find a for(u)m that accommodates the mess, that is the task of the artist now. (Samuel Beckett)

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Re: Why is this position evaluated so?

Post by soheil_hooshdaran » Thu May 11, 2017 3:55 am

Why would 1.Rb1 give White the advantage in:

Roger de Coverly
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Re: Why is this position evaluated so?

Post by Roger de Coverly » Thu May 11, 2017 9:08 am

soheil_hooshdaran wrote:Why would 1.Rb1 give White the advantage
#

With an extra pawn, you might expect any sensible move of the threatened Rook to retain an advantage. That said, I'm not sure how White makes progress after 1. Rb1 Nc5. Perhaps Black is almost in Zugswang as moves for Black are also difficult to find.

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Christopher Kreuzer
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Re: Why is this position evaluated so?

Post by Christopher Kreuzer » Thu May 11, 2017 10:51 am

Roger de Coverly wrote:
soheil_hooshdaran wrote:Why would 1.Rb1 give White the advantage
#

With an extra pawn, you might expect any sensible move of the threatened Rook to retain an advantage. That said, I'm not sure how White makes progress after 1. Rb1 Nc5. Perhaps Black is almost in Zugswang as moves for Black are also difficult to find.
After 1. Rb1 Nc5, doesn't 2. a5 break things up and leave the knight with almost nowhere useful to go?

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Re: Why is this position evaluated so?

Post by Roger de Coverly » Thu May 11, 2017 11:40 am

Christopher Kreuzer wrote: After 1. Rb1 Nc5, doesn't 2. a5 break things up and leave the knight with almost nowhere useful to go?
That does look to be a useful idea. But why b1 for the Rook ? There is the point that if the Rook leaves the b file, then b7 is available to the Knight, whilst if the Rook isn't on the first rank, then .. Ne1 check looks possible, with the idea of .. Ng2 .

It's a position where a bit of analysis of what happens next is needed in order to establish where the pieces should go.

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Re: Why is this position evaluated so?

Post by soheil_hooshdaran » Mon May 22, 2017 4:34 am

What'd be the White's advantage in:

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IM Jack Rudd
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Re: Why is this position evaluated so?

Post by IM Jack Rudd » Mon May 22, 2017 12:00 pm

It consists largely of having a bunch of pieces well placed to attack the black king. Black's pieces, by contrast, are well placed neither to defend his kingside nor to help drum up counterplay elsewhere.

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