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Old 2014-06-14, 20:34   #1
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[QUOTE=LaurV;375798]as it is same obvious that we won this game,[/QUOTE]NO! Black has plenty of fight left if we make just one mistake.

[quote]looking to the versions you both posted, there is no way we don't get out of this with a figure.[/quote]There are still variations where Black can hold us to only an Exchange advantage. His pieces are well-placed for battle on the a-file ... but that means we can clean up on the g/h-files if we're careful.

[QUOTE=cheesehead;375669]
[B]31 ... Bxc3 32 Nxe6+[/B] which leaves Black only one legal move: [B]32 ... Kd7[/B] [/QUOTE]There's another way, which involves shifting our focus away from the bcd678 area in order to make more widespread threats that overload Black's ability to defend.
[B]
32 Nb5[/B] deters ... Nd4+, attacks the B/c3, prevents Kc7. It lets off attacking the B/c8, but that B's still pinned for now. Square b5 turns out to be handy for a knight outpost while we struggle to eliminate Black's a-file threat.

If [B]32 ... Bb4 33 Nxe6+[/B]. Now, if Black tires to un-pin his B/c8 by [B]33 ... Kd7[/B], we force a re-pin with [B]34 Nf8+[/B], and if Black isn't careful:

If [B]34 ... Ke8 35 Nxg6[/B] we win a pawn by overloading double defender N/e7.
If [B]35 ... Nxg6 36 Rxc8+[/B] and we've increased our material lead to Exchange+pawn.

Furthermore, now our rook is unleashed!

If [B]36 ... Kd7 37 Rc7+[/B]
([B]36 ... Ke7 or Kf7 37 Rc7+[/B] will be pretty much the same road as follows if Black doesn't retreat his king to his back rank.)

If [B]37 ... Ke6 38 Rc6+[/B] forces Kf5 or Kf7.

If [B]38 ... Kf5 39 Nd4+[/B]. Now, Black either trades knights via [B]39 ... Ke5 40 Rxg6 Kxd4[/B] (and our rook will clean up the h6-pawn, giving us connected passers, before turning its attention to the a-file battle)
or Black fails to keep his knight via [B]39 ... Kg5 40 h4+ Kh5 41 g4+[/B] and [B]42 Rxg6[/B] -- we now have a full rook advantage, and Black's king is far away from the a-file battle.

If Black retreats his king to the back rank on move 37, we can tempt him to move one of his pieces onto the same file as his king, whereupon our rook will fork the two.

[speculation] 37 ... Kd8 (Ke8 or Kf8 would be similar) 38 Rc6 Ne5 39 Rxh6 Nc4 40 Bc6 Nb2 41 Nd4 Bc3 42 Nf5 Kc7 43 Bb5 Bb4 44 Kf2 Ne4+ 45 Ke3 Nc3 46 Nd4 (not 46 ... Bc5 47 Rc6+) Nbxa4 47 Bxa4 Nxa4 48 Nc6 Bc5+ 49 Kd3 Bb6 50 Ne5 Nb2+ 51 Kc3 Na4+ 52 Kb3 Nc5+ 53 Ka3 a4 54 Nc4 Ba7 55 Nb2

Of course, during that speculation there was a point where advancing our g/h pawns would lead to the fastest win, but I wanted to show a tough fight for the a-file.

- - -

Now, rewind to move 34, after [B]31 ... Bxc3 [/B][B]32 Nb5[/B][B] Bb4 33 Nxe6+[/B][B]Kd7[/B] [B]34 Nf8+[/B]:

If [B]34 ... Kd8 35 ????[/B]

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Old 2014-06-15, 03:24   #2
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[QUOTE=cheesehead;375839]NO! Black has plenty of fight left if we make just one mistake.[/QUOTE]Perhaps ... I was ... a bit ... hasty ... there.

While that "fight" statement is literally true, if [U]Black[/U] makes a mistake or two we may get near to a checkmate. (e.g., 31 ... Bxc3 32 Nxe6+ Kd7 33 Nxc8 Kxe6 34 Bh3+ Kf6 35 Rb6+ Kf7 36 Be6+ Ke8 37 Nd6+)

From Black's point of view, we are threatening 32 Nxe6+ forking king and B/g7. So, moving either his king or his B/g7 isn't just a good idea ... it's sort of mandatory, from Black's perspective. We can set aside analysis for any other possibility, I think.

It's almost certainly going to be 31 ... Kc7 or 31 ... Bxc3 or maybe 31 ... Bf6 or 31 ... Bf8 (not 31 ... Be5 which falls prey to a fork from our other knight).

So, let's start with the less likely and work up:

If [B]31 ... Bf8 32 Nxe6+ Kd7 33 Nxf8+ Kxd6 34 Nxg6[/B] The N/e7 is an overloaded defender.

If [B]34 ... Nxg6 35 Rxc8[/B] threatens 36 Rc6+ winning the N/g6. Our superior long-range mobility of R and B can out-dance Black's two knights.
If [B]35 ... N-moves 36 Rd8+[/B] wins the N/d2.

If [B]34 ... Kd7 35 Nxe7[/B] Just as the N/e7 was an overloaded defender last move, so too is Black's king now. We're a whole rook up.

-

If [B]31 ... Bf6 32 Nxe6+ Kd7 33 Nxc8[/B]
If [B]33 ... Kxe6 34 ????[/B]
If [B]33 ... Nxc8 34 Bh3[/B] threatens discovered attacks on K and N/c8.
If [B]34 ... Na7 35 Rb7+[/B]
If [B]34 ... Nd6 35 Nf8+ (not 35 Rd8+ Bxd8)[/B]
If [B]35 ... Ke7 36 Nxg6+[/B] and we just keep nibbling ...
If [B]35 ... Kc6 36 Bg2+[/B]
If [B]36 ... N2e4 37 ????[/B]
If [B]36 ... N6e4 37 Rxd2[/B] (taking advantage of the pin) and we're a rook up.
If [B]36 ... Kc7[/B]
[speculation] 37 Rb2 Bxc3 38 Rc2 N2e4 39 Nxg6 Kd7 40 Nf4 Bd4+ 41 Kf1 - we're up an Exchange+pawn

If [B]35 ... Ke7 36 ?????[/B]

- -

Have to stop now.

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Old 2014-06-16, 16:06   #3
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Between our choices after [B]31 ... Bxc3[/B],

[B]32 Nxe6+[/B] is the branch we've looked at longer, and we've probably uncovered/eliminated all possible traps/tricks by Black on the next few moves.

But [B]32 Nb5[/B], while easing up on the B/c8, sets up an outpost that covers important dark squares c3, d4, d6, c7 and a7 - especially significant as long as Black still has his dark-square bishop. It makes it hard for Black's dark-square bishop to find a place from which to interfere with our attack.

[QUOTE=cheesehead;375839]Now, rewind to move 34, after [B]31 ... Bxc3 [/B][B]32 Nb5[/B][B] Bb4 33 Nxe6+[/B][B]Kd7[/B] [B]34 Nf8+[/B]:

If [B]34 ... Kd8 35 ????[/B][/QUOTE](Caution: Some of the following analysis is not rigorous, although I don't label it with [speculative]. I'm just trying to quickly explore possibilities after [B]32 Nb5[/B].)[B]

35 Bb7[/B] attacks the B/c8 again _and_ gives our king a breathing square. Its threat 36 Bxc8 would pull the N/e7 into the pin we've established.

If [B]35 ... Bc5+ 36 Kg2[/B],
[B]36 ... Bb6[/B] looks like a blunder at first glance because of the discovered attack by our rook after
[B]37 Bxc8[/B], but after
[B]37 ... Nxc8[/B] it is our rook which is double-tasked: it can't take the B/b6 without releasing the pin on that piece's then-defending N/c8. However, we can re-purpose our N/b5 with
[B]38 Nd6[/B] and
if [B]38 ... Bc7 39 Rxc8+ Ke7 40 Rxc7+[/B] and after 40 ... Kxd6 or Kxf8 our full-rook advantage will win. (38 ... Ba7 doesn't help, either: 39 Rxc8+ Ke7 40 Rc7+ results in the same rook-advantage for us.)

So, it looks to me as though 32 Nb5 and 32 Nxe6+ are about equal in merit if Black plays 31 ... Bxc3, especially since the N on b5 could return to our attack in a single move, and Nxe6+ turns out to be a likely followup to Nb5.

-

Suppose that after [B]31 ... Bxc3 32 Nb5[/B], Black moves the B/c3 somewhere other than b4 -- how much threat can it be?

[B]32 ... Be5[/B] seems the only other reasonable choice. Then
[B]33 Ra8[/B] retains the pin and additionally attacks the a5-pawn. Now,
[B]33 ... Nc4[/B] protects a5, but
[B]34 Bb7[/B] brings our remaining B into the attack, threatening 35 Bxc8 which drags the black N/e7 into the pin.
If [B]34 ... Nb6 35 ????[/B]
If [B]34 ... Nd6[/B]
If [B]35 Nxd6+ Bxd6[/B]
If [B]36 Nxe6+ Kd7 37 Bxc8+ Nxc8[/B] the B/d6 is powerful. If 38 Nd4 Bc5. If 38 Nf8+ Bxf8. If 38 Ng7 Bf8. So we'd better avoid this line --- but _how_, if Black plays [B]32 ... Be5[/B] after [B]32 Nb5[/B]?

If [B]32 ... Bxc3 33 Nb5 Be5 34 ????[/B]
In fact,
have we yet considered whether Black can insert ... Be5 somewhere in our analysis after [B]33 Nxe6+ Kd7 34 Nxc8[/B] ?

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Old 2014-06-16, 17:34   #4
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31 ... Bxc3 32 Nb5 Bb4 33 Nxe6+Kd7 34 Bh3 may be better.
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Old 2014-06-16, 19:59   #5
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The mystery is over:

[URL="http://www.mersenneforum.org/showpost.php?p=375970&postcount=151"]31...Bxc3[/URL] at 16 Jun 14, 17:02

Our deadline (with one-hour margin) is Monday, June 23 16:02 GMT
= Monday, June 23 23:02 Thai time
= Monday, June 23 12:02 EDT
= Monday, June 23 11:02 CDT

- - -

Move-number typos (unless I'm mixed up _now_) in a previous posting:
[QUOTE=cheesehead;375962]
If [B]32 ... Bxc3 33 Nb5 Be5 34 ????[/B]
In fact,
have we yet considered whether Black can insert ... Be5 somewhere in our analysis after [B]33 Nxe6+ Kd7 34 Nxc8[/B] ?[/QUOTE]should've been:

If [B]31 ... Bxc3 32 Nb5 Be5 33 ????[/B]
In fact,
have we yet considered whether Black can insert ... Be5 somewhere in our analysis after [B]32 Nxe6+ Kd7 33 Nxc8[/B] ?



- - -

[QUOTE=WMHalsdorf;375971]31 ... Bxc3 32 Nb5 Bb4 33 Nxe6+Kd7 34 Bh3 may be better.[/QUOTE]Could be, but I now think Black won't cooperate with a meek 32 ... Bb4. I expect 32 ... Be5 in that line.

- - -

Sometime earlier I mentioned something about capturing his pieces faster than he can capture ours. IMO it's a sound principle (though I don't recall reading it in any chess book -- perhaps because I have more strategy books than tactics books!), and 32 Nxe6+ is more consistent with that than 32 Nb5.

Also as mentioned before, I think it's less likely that after 32 Nxe6+ there's some unpleasant surprise waiting for us than after 32 Nb5. It took me a while (too long IMO) to notice the strength of 32 ... Be5 after I started analyzing 32 Nb5, and I consider that a caution signal.

And though 32 Nb5 does attack the B/c3, it removes an attacker from the B/c8. Spending a precious tempo merely to switch targeted bishops doesn't seem like the best idea unless there's a really good reason. Our N/d6 is strong where it is, and it's already attacking a bishop (one that won't move!).

Now, I _do_ think that eliminating Black's black-squared bishop (in preference to the light-squared one) is a good idea ... but the dark-squared B won't be staying where we attack it. Since Nxe6+ happens [I]also[/I] to deter the most troublesome move (... Bd4+) of the dark-squared B, in addition to the primary reason we've been considering Nxe6+, I'm now in favor or doing that.

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Old 2014-06-16, 22:27   #6
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As I looked closer at Nb5 it feel it leaves Black with to much wiggle room in the form of number of pieces on the board. Prefer Nxe6+ forcing Kd7 followed with Nxc8.
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Old 2014-06-17, 10:16   #7
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Yeah, we have more grip on the position in that line.

"Grip" like ... winning by force, I now think. (But I've been wrong about that before.)

- - -

[B]32 Nxe6+ Kd7 33 Nxc8[/B] Black's a piece down, so here has only two viable options -- 33 ... Kxe6 or 33 ... Nxc8. Since he can't do Bd4+ until after he's eliminated our N/e6, I'd bet that's (33 ... Kxe6) what they do.

If [B]33 ... Kxe6[/B] Now if we can pin the N/e7 to Black's king, we can win -- by eliminating the a5-pawn. That requires persuading Black to move his king to f7.

If [B]34 Bh3+[/B] gives our king another flight square in case of future check from Bd4+ or Bc5+, and reduces the number of squares from which the Black king can defend the N/e7.
If [B]34 ... Kf6 35 Rb6+ Kf7[/B] (or else loses the N/e7) [B]36 Rb7[/B]. Now the N/e7 is both pinned and double-attacked. To keep it, Black must use his B.
[B]36 ... Bb4 (or Bf7) 37 Nxe7 Bxe7[/B]. Now that we've pulled the B off a5-defending duty,
[B]38 Ra7[/B] threatens 39 Rxa5. Black can protect with his N.
[B]38 ... Nc4[/B] (not ... Nb3 39 Rxb3). (Now, if only we could play Bd5+, that'd be the game.)
[B]39 Bf1[/B] threatens Bxc4, finally enabling Rxa5. Black could try to distract us with 39 ... Nd2 or ... Ne3, but we can ignore those long enough to nab the a-pawn. Black can not stop us.
If [B]39 ... N-move 40 Rxa5[/B] and we have a win.
If [B]39 ... not N-move 40 Bxc4[/B] and we have a win.

If [B]34 ... Kf7[/B] will be the same as after [B]34 ... Kf6[/B] except that we establish the pin one move earlier: [B]35 Rb7[/B]. Win.

- -

If [B]33 ... Nxc8[/B], With our N/c8 gone, we can't win immediately by force as shown above for 33 ... Kxe6. We could try eliminating Black's a-pawn, but so far I haven't found a way to get around Black's defense there.

[B]34 Nf8+[/B]
If [B]34 ... Kd8 35 Bh3[/B] wins the N/c8.
If [B]34 ... Kc7 35 Rb7+ and 36 Nxg6 and ?????[/B]. We use our rook both to deter Nb6 (attacking our a-pawn) and to keep Black's king away from (whichever edge of the board we want to keep it away from). We eliminate Black's king-side pawns (while preventing Black's a-pawn from advancing), so that our connected g-h passers become decisive. Probable win, though direct path is not yet clear.
If [B]34 ... K-other 35 Rxc8[/B] wins.

- - -

Vote:

32 Nxe6+ -- 5

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Old 2014-06-17, 16:22   #8
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[QUOTE=cheesehead;376012]<snip>
[B]36 ... Bb4 (or Bf7) 37 Nxe7 Bxe7[/B]. Now that we've pulled the B off a5-defending duty,
[B]38 Ra7[/B] threatens 39 Rxa5. Black can protect with his N.
[B]38 ... Nc4[/B][/QUOTE][strike](not ... Nb3 39 Rxb3)[/strike] Oops. R is not on b-file anymore, so ... Nb3 is also possible.

Revision:
[B]38 Ra7[/B] threatens 39 Rxa5, [B]but now it's on the same diagonal as our king, so before Black's B can move again, we must move our king (or rook) !![/B]
Black can protect a5 with his N.

If [B]38 ... Nc4 39 Bf1[/B] _seems_ to chase the knight, but
If [B]39 ... Kf6 or Kf8[/B] (Ke6 or Ke8 would leave the king vulnerable to a check from our B) the B/e7 is no longer pinned!
Here, 40 Bxc4 would lose our rook to 40 ... Bc5+. So we must first move our king!
[B]40 Kg2[/B]. Now, we're free of fear of bishop skewer of our king and rook ... but there are other concerns.
If [B]40 ... Ne3+ 41 Kf2 Nxf1 42 Kxf1 Bb4[/B].
Now Black has made it necessary for our king to travel to assist our rook if we want to capture the a-pawn. But if we were to do exactly that, his king could travel down to take our g-h pawns and march his connected g-h passers down to victory. (I'm not going to try counting moves to see whether we could win a king/pawn-race.) However, by themselves the Black a-pawn and B/b4 pose no offensive threat. Our a-pawn can continue to block theirs by itself, while we switch our rook to the king-side.
If [B]40 ... Nd3 or Nb3 or Na2 or Nb6 or Nd6 or Ne5 41 Rxa5[/B].
If [B]40 ... Bc5[/B] now we have to move our rook to a6 or a8 (whichever gives check) then 42 Bxc4 and we're a rook up.

If [B]38 ... Nb3[/B][B] 39 Bf1[/B] threatens 40 Bc4 attacking the N/b3.
If [B]39 ... Kf6 or Kf8[/B] the B/e7 is no longer pinned, so
[B]40 Kg2[/B] and now we go into variations similar to those after [B]38 ... Nc4[/B] above.

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Old 2014-06-17, 16:55   #9
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Since Black will have only _one_ legal move after [B]32 Nxe6+[/B], I think this is a unique situation in which an if-move should be acceptable. [I]However[/I], in view of previously-expressed preference by the Gekkota captain, [I]and[/I] since even a forced-move if-move [I]could[/I] be construed as cutting into Black's analysis time[/sup]*[/sup] (which they're undoubtedly also spending on possible moves far beyond the next one), [I]and[/I] since Black [I][U]has[/U] been prompt[/I] with their replies (not taking the whole week) lately ... I'll try to be patient.

[sup]*[/sup] [U]OTOH, the if-move here could actually be construed as [B]favorable[/B] to Black's analysis time, because they could drop their analysis of all our move 33 possibilities besides 33 Nxc8[/U] !!!

- -

So, now I'm in favor of the if-move again.

Vote:

[I]"32 Nxe6+

Since there's a single legal reply, and in order to save Black's analysis time of White move 33 possibilities we don't intend, we commit ourselves to:
If 32 ... Kd7 33 Nxc8

For deadline purposes, we're willing to allow Black a week to post their move 32 and then another week to post their move 33, if they wish to take both weeks."[/I]

We could also say we intend not to post any other if-move unless there's also only a single legal possibility. Also, we propose that the if-move poster assumes all responsibility for deciding that there is not more than one legal reply.

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Old 2014-06-17, 22:03   #10
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This requires an if move since it's a forced move, so why give them what amounts to 2 weeks to make a reply.
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Old 2014-06-18, 00:10   #11
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I still strongly disagree with LaurV's reasoning expressed a couple of moves ago. If-moves have been used in postal chess for over a century with no connotation of impoliteness or insult.

In fact, two of LaurV's points are [U]exactly backwards![/U]

A) It's no insult to openly acknowledge that there's only one legal reply. Actually just the reverse:
Waiting for the opponent to post the obvious only possibility is the insult to the opponent's intelligence. [I]It pretends that the opponent needs time to figure out the only legal move[/I], instead of simply openly acknowledging the simple fact of there being no alternative and getting on with the next move after that.

B) As for cutting into the opponent's time: no, it [U]extends[/U] the amount of time the opponent can use for analysis since he doesn't have to analyze any of the alternatives that might have been played instead of the declared if-reply.

- - -

[QUOTE=WMHalsdorf;376085]This requires an if move since it's a forced move, so why give them what amounts to 2 weeks to make a reply.[/QUOTE]

Because it's a polite thing to do (NOT an impoliteness as one of the backward arguments above would have it).

- - -

However, I withdraw my proposal to post anything but

32 Nxe6+

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