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Old 2014-06-24, 06:00   #23
LaurV
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I had a better look last night, but it was too late (or too early in the morning, hehe) to post any analysis. As the timeout is tonight (my time), just to prepare for the event I can't post, my vote stands like this (see below), and you can post any of these moves anytime, in case I don't login again this evening. (I have to go to some "party" with my daughter who just finished grade 10, I hope I can login, at least to post the move, before 11).

[B]33 Nb5 [/B]- 5 points, I still consider it the fastest and clearest way to win, the best way to transform our pawn or take a black heavier piece with it if it dies.

[B]33 Nxc8 [/B]- 4 points - you almost convinced me that this is the best move, but it still seems for me that winning effectively (the end-game phase) is still longer and not so straight.

[B]33 Rb6[/B] - 3 points - this seems to be a good move to win too, but I didn't go very deep into it, that is why only 3 points. Anyhow, black seems lost in any case.

Any other move - 0 points.

You were somehow right that the game is not yet fully decided, we may end up playing a rook against a horse and a pawn, or so, and this is not always a win situation. That may be why the struggle to make the pawn free, and eventually, transform it, can be important right now.
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Old 2014-06-24, 12:27   #24
LaurV
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:davieddy: The due date is Thursday, not Tuesday! Somehow it remained to my brain that the due date was today...
We still have time to think :razz:
(not so much to think about, however)
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Old 2014-06-24, 17:18   #25
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I'm now leaning toward 33 Nb5, too -- partly because of the following discovery:

- -

Here's a plausible, sometimes-forcing line that leads toward my fond wish of trading one of our knights for Black's dark-square bishop:

[B]33 Nb5 Be5[/B] (presuming that this is Black's best move) [B]34 Nc5+ Kd8[/B] (presuming that this looks better to Black than ... Ke8) [B] 35 Ra8 Nc4 36 Bb7[/B] (not Bh3 Nb6 37 Rxa5 Bxh3) [B]36 ... Nb6 37 Rxa5 Bxb7[/B] (presuming that this looks attractive to Black after having the B/c8 bottled up for so long) [B]38 Nxb7+[/B]

Now, if Black moves his king to c8 or e8 (instead of d7):
[B]38 ... Kc8 or Ke8 39 N5d6+[/B] (not N7d6+ which doesn't uncover the rook attack on the B/e5) [B]39 ... Bxd6[/B] is forced (not 39 ... K-moves 40 Rxe5) [B]40 Nxd6+[/B] and Black's most powerful piece is gone.

- -

Here's a current dump of my messy [B]33 Nb5[/B] analysis tree. Watch out for sections that don't belong where they are!

(The sequence above is about one-third of the way down.)
[B]
33 Nb5[/B]

If [B]33 ... Be5[/B] threatens to take our rook

If [B]34 Nf8+[/B]
If [B]34 ... Kc7 35 Rb7+ Kxc8 36 Rxe7 Bd4+ 37 Kh1 Bc5 38 Re8+ Kc7 39 Ne6+ Kd7 40 Rd8+ Kxe6 41 Rxd2[/B]

If [B]34 ... Kd8 35 Nxe7+[/B]
If [B]35 ... Kxe7 36 Nxg6+[/B]

If [B]34 ... Ke8 35 Nd6+ Nc8 36 Rxc8+ Ke7 37 Nb5[/B] threatens 38 Nxg6+
If [B]37 ... Bd4+ 38 Nxd4[/B]

If [B]33 ... Bb4[/B]
If [B]34 Nf8+[/B]
If [B]34 ... Kd8 35 Nxg6[/B]
If [B]35 ... Nxg6[/B]
If [B]36 Rxc8+[/B]
If [B]36 ... Kd7 37 [/B]
If [B]36 ... Ke7 37 [/B]
If [B]34 ... Ke8 35 Nxg6[/B]
If [B]35 ... Nxg6[/B]
If [B]36 Rxc8+[/B]
If [B]36 ... Kd7 37 [/B]
If [B]36 ... Ke7 37 [/B]
If [B]36 ... Kf7 37 [/B]

- - *

If [B]34 Nc5+[/B]

If [B]34 ... Kd8 35 Ra8 Nc4[/B]
If [B]36 Bb7[/B] (not Bh3 Nb6 37 Rxa5 Bxh3) [B]36 ... Nb6 37 Rxa5 Bxb7 38 Nxb7+[/B]
- -
If [B]38 ... Kc8 39 N5d6+ Bxd6[/B] (not 39 ... K-moves 40 Rxe5) [B]40 Nxd6+[/B] - a long-desired accomplishment of trading one of our knights for Black's powerful dark-square bishop!
-
If [B]40 ... Kb8 41 Rb5[/B]
If [B]41 ... Ned5 42 ????[/B]
If [B]41 ... Ka7 42 ????[/B]
If [B]41 ... Kc7[/B] threatens both 42 ... Kxd6 and 42 ... Nxa4
If [B]42 a5[/B]
If [B]42 ... Kxd6[/B]
If [B]43 axb6[/B]
If [B]43 ... Kc6[/B]
If [B]44 Rb3[/B]
If [B]44 ... Kc5[/B]
If [B]45 b7 Nc6 46 Re3[/B]
If [B]46 ... Kb6 47 Re6 Kxb7 48 Rxg6[/B] Win
If [B]46 ... Kd6 47 Kf2[/B]
If [B]47 ... Kc7 48 Re6 Kxb7 49 Rxg6[/B] Win
If [B]44 ... Kb7 45 Kf2 Nd5(or Nc8) 46 Kf3 Nxb6 47 Ke4[/B] Win
If [B]43 Rxb6+ ????[/B]
-
If [B]40 ... Kc7 41 ????[/B]
-
If [B]40 ... Kd7 41 ????[/B]
-
If [B]40 ... Kd8 41 ????[/B]

- -

If [B]38 ... Ke8 39 N5d6+ Bxd6[/B] (not 39 ... K-moves 40 Rxe5) 40 Nxd6+[/b]
-
If [B]40 ... Kd7 41 ????[/B]
-
If [B]40 ... Kd8 41 ????[/B]
-
If [B]40 ... Kf8[/B]
If [B]41 Ra6[/B]
If [B]41 ... Ned5[/B]
If [B]42 a5[/B]
If [B]42 ... Na4 43 Rc6[/B]
If [B]43 ... Nb4 44 Rc4[/B] wins a knight
If [B]43 ... Ne7 44 Rc1[/B]
If [B]44 ... ????[/B]
If [B]42 ... Nd7 43 ????[/B]
If [B]41 ... ????[/B]

- -

If [B]38 ... Kd7 39 Ra6[/B]
If [B]39 ... Kc6 40 N7d6[/B]
If [B]40 ... Bxd6 41 Nxd6[/B]
If [B]41 ... Kxd6 42 Rxb6+[/B] Win
If [B]41 ... Ned5(not Nec8 42 Nxc8) 42 Nc8[/B] Win
If [B]41 ... Kc5 42 Kf2[/B]
If [B]42 ... Nbd5 43 Kf3[/B]
If [B]43 ... ????[/B]
If [B]42 ... Nbc8 43 ????[/B]
If [B]42 ... ????[/B]
If [B]41 ... Kc7 42 Nc4[/B] Win

If [B]37 ... ????[/B]

If [B]36 ????[/B] (not Bh3 Nb6 37 Rxa5 Bxh3)

- = * - = *

If [B]34 ... Ke8 35 Ra8 Nc4[/B]
If [B]36 Bb7[/B]
If [B]36 ... Nb6 37 Rxa5[/B]
If [B]37 ... Bxb7 38 Nxb7[/B]

[B]38 ... Kd7[/B]
What if 38 ... Ke8 ?

[B]39 Ra6 Nec8[/B]
What if 39 ... Nbc8 or Nbd5 or Ned5 ?

[B]40 a5 Kc6[/B]
What if 40 ... Nd5 ?

[B]41 Nb7d6 Nxd6[/B]
What if 41 ... Bxd6 ?

[B]42 Rxb6 Kd7 43 a6 Nxb5[/B]
What if 43 ... Nc8 ?

[B]44 Rxb5 Bd4 45 Kg2 Kc6 46 Rb7[/B]
Suppose 46 ... Bb6
If 47 a7 Kxb7 48 ????
If 47 Rb8
If 47 ... Kc7 48 ????
If 47 ... Ba7 48 ????

- - - - - - - - - - - - - - - -

... and I have to leave it at that for now.

Last fiddled with by cheesehead on 2014-06-24 at 17:48
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Old 2014-06-25, 18:35   #26
cheesehead
 
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Now, after more exploration, I'm favoring [B]33 Nxc8[/B] over [B]33 Nb5[/B] again.

It's true that if Black doesn't play exactly right in either line, then we can win decisive material within the foreseeable future. But in team week-per-move play, [I]we should presume that Black will discover and avoid all the mistakes that have not-too-distant consequences.[/I]

If Black does avoid such mistakes, we are left to use forcing moves and long-horizon strategic moves to increase our advantage. We are the side with the most forcing moves, through our pieces' proximity to the Black king, and we are the side that ought to have the best long-horizon strategic moves, through our material advantage and ability to exploit vulnerabilities in Black's position.

The key position in the [B]33 Nb5[/B] line results after we've responded to Black's immediate counter-threats, and have an opportunity to freely choose one of multiple ways to continue:

[B]33 Nb5 Be5 34 Nc5+ Kd8 35 Ra8 Nc4[/B] (threatening ... Nb6 to end our rook's pin of the B/c8) [B]36 ????[/B]

Note that in this position:

a) Black has been able to bring both of his most-distant pieces (the B/c3 and N/d2) back into play with immediate impact on our ability to pursue attacking. All of Black's two bishops and two knights are in the abcde45678 battle sector. In particular, Black's dark-square bishop has caused us to let up pressure on the Black king.

b) [I]We've not yet captured a single Black man[/I] in order to increase the importance of our material advantage or reduce Black's ability to fight.

c) None of our obvious follow-ups Nb7+, Bb7 and Bh3 will gain much once Black is able to get in his move ... Nb6.

Now, let's compare the [B]33 Nxc8[/B] line's two key positions:

[B](1) 33 Nxc8 Kxe6 34 Bh3+ Kf6 35 Rb6+ Kf7 36 Rb7 Bb4(or Bf6) 37 Nxe7 Bxe7 38 Ra7 Nb3[/B].

Here, we've already swapped down two pairs of pieces toward a rook vs. minor-piece endgame. Black's freedom of movement is temporarily restricted -- his knight is on pawn-guard duty and his bishop is pinned. OTOH, we face the counter-threat of Bc5+ rook-winning fork when Black moves his king to negate the pin, so ought to move our king or rook before the Black bishop can again move ... but an immediate Kf1 or Kg2 interferes with our bishop's freedom to maneuver.

[B](2) 33 Nxc8 [/B][B][B]Nxc8[/B] 34 Bh3 Nd6 35 Nf8+ Kc7 36 Ra8 Kb6 37 Nxg6[/B].

Here, we've swapped down one pair of pieces and captured a king-side pawn to leave Black with an isolated rook pawn there. Our connected king-side pawns cannot easily be threatened by Black, and after more swap-downs may be decisive in the endgame. Though Black seems better poised for battle over the a-pawns, our bishop can guard a4 with one move, while our rook can keep the Black king from attacking our a4 with Rb8.

I think we're closer to a win in either [B]33 Nxc8[/B] line's key position than in the [B]33 Nb5[/B] line's key position.

So I vote:

33 Nxc8 -- 5
33 Nb5 -- 3

Last fiddled with by cheesehead on 2014-06-25 at 19:00
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Old 2014-06-25, 23:02   #27
WMHalsdorf
 
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With both knight moves being almost identical in value I prefer
33 Nxc8 (5 pts) over 33 Nb5 (4 pts) just because it requires Black to dig to a deeper level to find the best move.
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Old 2014-06-26, 02:31   #28
LaurV
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Ok, plain and clear. I will post 33 Nxc8, and get rid of it :smile:
They are dead anyhow :razz:
(as a side observation, this game is longer and heavier than the first game! It seems that indeed, black has a bit of advantage in the game when the sicilian defensive is played)
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Old 2014-06-26, 04:31   #29
cheesehead
 
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The Sicilian deservedly has a long history as a powerful defense. It's part of the reason (a) I rarely play 1 e4 as White over-the-board, and (b) why I like to open with the Sicilian's English counterpart 1 c4.

But my experience in this game will counter some of my reluctance to face the Sicilian as White, or play the Sicilian as Black, as I've been forced to face positions I don't ordinarily see. Thanks again to you guys for helping to keep me out of my usual rut!
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Old 2014-06-26, 16:48   #30
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[QUOTE=cheesehead;376494]I just found that in my favorite [B]33 Nxc8 Kxe6 34 Bh3+[/B] line, Black does have at least one defensive sequence that avoids losing his a5-pawn, so I retract my claim that we have a forced win of material there.[/QUOTE]Now I've discovered how to tighten the sequence that Black has to tread in order not to lose material.

[quote][B]33 Nxc8 Kxe6 34 Bh3+ Kf6 35 Rb6+ Kf7 36 Rb7 Bb4 37 Nxe7 Bxe7 38 Ra7[/B][/quote]If [B]38 ... Nb3 or Nc4[/B] then[B]
39 Ra6[/B] threatening 40 Be6+ winning the knight (on either b3 or c4)

If [B]39 ... [I]any N-move[/I] (from either b3 or c4)[/B]
then [B]40 Rxa5[/B] ([U]NOT Rxb6[/U] if the N moved there from c4, because of 40 ... Bc5+!!)

If [B]39 ... Bc5+ 40 Kg2[/B] (NOT Kf1 Nd2+ 41 K-move Bb4 protecting both knight and pawn) and now we still have the same threats to capture pawn or knight as we did before.

If [B]39 ... Bd6 40 Rxd6[/B]

If [B]39 ... any other B-move except Bc5 or Bd6 40 Be6+[/B] winning the knight (on either b3 or c4)

If [B]39 ... any pawn-move 40 Be6+[/B] winning the knight (on either b3 or c4)

But I'm still examining cases where on move 39 the king moves to certain squares with the knight on b3 or to certain other squares with the knight on c4, so that 40 Be6 does not check the king and Black can move something else on move 40.

Last fiddled with by cheesehead on 2014-06-26 at 17:03
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