White 24 - Page 3

cheesehead · 2014-03-27, 02:56

Maybe if I don't call this the final draft, it will become one.

- -

(In most of the following cases, Black can interpolate with ... bxc3 bxc3 before Nxd4, with no change in material balance at the end. I've not yet thoroughly scanned for cases where Black can do that to his advantage.)

[B]A) 24 Rxf6 Bxf6[/B]
[B]
-

[/B]If[B] 25 Be3[/B]
Now 25 ... Nxd4 is not dangerous because Black's dark-square rook can't really fork anything. We just re-take with 26 cxd4 or 26 Bxd4 Bxd4+ 27 cxd4.

Verdict: [B]25 [/B][B]Be3[/B] not compelling

-

If [B]25 Ne4[/B]
Now [B]25 ... Nxd4[/B] is not dangerous because of 26 Nxf6+ and there's no bishop fork.
The immediate [B]25 ... Bxd4+[/B] does not fork anything, either: After 26 cxd4 Nxd4 we have three pieces clustered just where we need them to neutralize Black's pawn-push threats in the southwest quadrant of the board. Black's advanced knight may be troublesome, but can't do real harm. We could even bring our king out a bit: 27 Kf2 prevents ... Ne2+. Or just 27 Ne3.
If 27 ... Nb3 28 Rb1 and we threaten both 29 Bxh6 and 29 Nd6+ and 30 Nxc4.
If 27 ... Ne2+ we just bring our king out with 28 Kf2.

If [B]25 ... Kf7[/B] 26 Rxf6+.

If [B]25 ... Bg7[/B] 26 Bf4 e5 27 dxe5 Nxe5 and [I]my previous analysis here was mixed-up[/I] 28 Ne3 threatens 29 Bxe5 and 30 Nxc4.

If [B]25 ... Bxd4+ 26 cxd4 Nxd4[/B] 27 Ne3.
If 27 ... Nb3 28 Rd1 (allows 29 Rxd2 if 28 ... Nxd2, so as not to pull the N/e4 off station). Now if 28 ... Ba6 29 Nd6+ and 30 Nxc4.
If 27 ... Ne2+ 28 Kf2 Nd4 29 Nxc4.
So, there's not much Black's N/d4 can do after 27 Ne3.
We may swap a knight for Black's other bishop via Nd6+, so as to be left with the two bishops in an open position.

Verdict: [B]25 Ne4[/B] has possibilities

-

If [B]25 Bf4[/B]

If [B]25 ... Ra8[/B] 26 Rc1 and we have possibilities like Bxh6, Bc7, Ne3. Our K and N/c5 are still on the d4 diagonal, but as long as we keep that in mind and have a pawn on c3, we're all right.

If [B]25 ... e5 [/B]Black threatens to eat down our pawn chain with 26 ... exd4 etc. Our c3 pawn is an essential part of our defense against the d4-fork threat, so we can't just ignore the e5 pawn ... unless we deliver a forcing check, that is.

If [B]26 Bxc6+ Nxc6[/B], the absence of the knight on e7 might be significant. Two significant differences from other lines we've analyzed are: Black no longer controls the d5 square, and the e-file in front of Black's king is open except only for the e5-pawn.
If we were willing to sac our remaining bishop, we could play Nf2 and Re1 (possibly a check). But after 27 Nf2 exf4 28 Re1+ we have very little force to bear near the Black king. Black can simply sidestep with 28 ... Kf7 or Kf8 or Kd8.
To take advantage of the weak d5 square, we have 27 Ne3 or 27 d5. 27 Ne3 exf4 28 Nd5 Kf7 29 Rf1 doesn't lead to anything but a drawn-out loss.
27 d5 Ne7 28 Bxh6 Nxd5 29 Ne3 Nxe3 30 Bxe3leaves us only a thin positional advantage (both of Black's king-side pawn are isolated) and Black's light-square bishop is likely to be more lively than our knight. A draw at best, I think.
So I see no advantage to 26 Bxc6+.

If [B]26 dxe5[/B] this choice gains us Black's h-pawn (as far as I can see)!

If [B]26 ... Nxe5 [/B]then [B]27 Ne3[/B] is not good: 27 ... g5 28 Bxe5 Bxe5 29 Nxc4 Bc7 looks evenish.Instead, [B]27 Bxh6[/B] and then:

If [B]27 ... Bf5[/B] 28 Be4 Bxe4 29 Nxe4.

If [B]27 ... g5[/B] 28 Ne4 (not 28 h4 gxh4 29 gxh4 Bxh4) and we not only free our bishop but take another pawn in the process:
If 28 ... Kf7 29 Bxg5.
If 28 ... Bh8 29 Bxg5.
If 28 ... either N moves(except Nf3+?) 29 Nxf6+ and 30 Bxg5.
If 28 ... Rb6 29 Nxf6+ and 30 Bxg5.

Verdict: [B]25 Bf4[/B] and if 25 ... e5 [B]26 dxe5 [/B][B][B]Nxe5[/B] [/B]could be good for us.

Backing up,
If [B]26 ... Bxe5 27 Bxh6[/B] but we must be careful until we get our N/d1 and R activated.
If 27 ... Bf5 28 Rc1 and I think our position holds together long enough for us to get our N/d1 out. (If 28 ... Bd3 29 Nxd3 cxd3 30 Nf2 bxc3 31 bxc3 Rb2 32 Nxd3)

Verdict: [B]25 Bf4 e5 [/B](best for Black) [B]26 dxe5 [/B][B]Bxe5 [/B](best for Black) [B]27 Bxh6[/B] gets us a pawn and struggle.

- -

[B]B) 24 Re1
[/B]is what seems to be the only feasible alternative to [B]24 Rxf6[/B], but it has a weakness.

Previously, I wrote:
If [B]24 ... bxc3 25 bxc3 R-f5/f7/f8[/B]. But after [B]26 Nxe6[/B] [b]Bxe6 27 Rxe6 Nxd4[/b] I don't like our position. Material and pawn structure is even, whereas after [B]24 Rxf6[/B] we still had threats on Black's weak pawns.

- - -

My FINAL vote:

Rxf6 - 5 points
Re1 - 0 points
Rc1 - 0 points
Bf4 - 0 point

cheesehead · 2014-03-27, 03:54

[QUOTE=cheesehead;369491]

Our deadline is [URL="http://mersenneforum.org/showpost.php?p=369483&postcount=134"]Thursday, March 27 12:40 GMT[/URL]

[/QUOTE]I've discovered that I seem to have been using "GMT" incorrectly, and that I should've been using "UTC" in its place.

GMT starts at noon, not midnight as I've been assuming.

UTC starts at midnight.

2014-03-27, 02:56	#23
cheesehead "Richard B. Woods" Aug 2002 Wisconsin USA 2²·3·641 Posts	Maybe if I don't call this the final draft, it will become one. - - (In most of the following cases, Black can interpolate with ... bxc3 bxc3 before Nxd4, with no change in material balance at the end. I've not yet thoroughly scanned for cases where Black can do that to his advantage.) [B]A) 24 Rxf6 Bxf6[/B] [B] - [/B]If[B] 25 Be3[/B] Now 25 ... Nxd4 is not dangerous because Black's dark-square rook can't really fork anything. We just re-take with 26 cxd4 or 26 Bxd4 Bxd4+ 27 cxd4. Verdict: [B]25 [/B][B]Be3[/B] not compelling - If [B]25 Ne4[/B] Now [B]25 ... Nxd4[/B] is not dangerous because of 26 Nxf6+ and there's no bishop fork. The immediate [B]25 ... Bxd4+[/B] does not fork anything, either: After 26 cxd4 Nxd4 we have three pieces clustered just where we need them to neutralize Black's pawn-push threats in the southwest quadrant of the board. Black's advanced knight may be troublesome, but can't do real harm. We could even bring our king out a bit: 27 Kf2 prevents ... Ne2+. Or just 27 Ne3. If 27 ... Nb3 28 Rb1 and we threaten both 29 Bxh6 and 29 Nd6+ and 30 Nxc4. If 27 ... Ne2+ we just bring our king out with 28 Kf2. If [B]25 ... Kf7[/B] 26 Rxf6+. If [B]25 ... Bg7[/B] 26 Bf4 e5 27 dxe5 Nxe5 and [I]my previous analysis here was mixed-up[/I] 28 Ne3 threatens 29 Bxe5 and 30 Nxc4. If [B]25 ... Bxd4+ 26 cxd4 Nxd4[/B] 27 Ne3. If 27 ... Nb3 28 Rd1 (allows 29 Rxd2 if 28 ... Nxd2, so as not to pull the N/e4 off station). Now if 28 ... Ba6 29 Nd6+ and 30 Nxc4. If 27 ... Ne2+ 28 Kf2 Nd4 29 Nxc4. So, there's not much Black's N/d4 can do after 27 Ne3. We may swap a knight for Black's other bishop via Nd6+, so as to be left with the two bishops in an open position. Verdict: [B]25 Ne4[/B] has possibilities - If [B]25 Bf4[/B] If [B]25 ... Ra8[/B] 26 Rc1 and we have possibilities like Bxh6, Bc7, Ne3. Our K and N/c5 are still on the d4 diagonal, but as long as we keep that in mind and have a pawn on c3, we're all right. If [B]25 ... e5 [/B]Black threatens to eat down our pawn chain with 26 ... exd4 etc. Our c3 pawn is an essential part of our defense against the d4-fork threat, so we can't just ignore the e5 pawn ... unless we deliver a forcing check, that is. If [B]26 Bxc6+ Nxc6[/B], the absence of the knight on e7 might be significant. Two significant differences from other lines we've analyzed are: Black no longer controls the d5 square, and the e-file in front of Black's king is open except only for the e5-pawn. If we were willing to sac our remaining bishop, we could play Nf2 and Re1 (possibly a check). But after 27 Nf2 exf4 28 Re1+ we have very little force to bear near the Black king. Black can simply sidestep with 28 ... Kf7 or Kf8 or Kd8. To take advantage of the weak d5 square, we have 27 Ne3 or 27 d5. 27 Ne3 exf4 28 Nd5 Kf7 29 Rf1 doesn't lead to anything but a drawn-out loss. 27 d5 Ne7 28 Bxh6 Nxd5 29 Ne3 Nxe3 30 Bxe3leaves us only a thin positional advantage (both of Black's king-side pawn are isolated) and Black's light-square bishop is likely to be more lively than our knight. A draw at best, I think. So I see no advantage to 26 Bxc6+. If [B]26 dxe5[/B] this choice gains us Black's h-pawn (as far as I can see)! If [B]26 ... Nxe5 [/B]then [B]27 Ne3[/B] is not good: 27 ... g5 28 Bxe5 Bxe5 29 Nxc4 Bc7 looks evenish.Instead, [B]27 Bxh6[/B] and then: If [B]27 ... Bf5[/B] 28 Be4 Bxe4 29 Nxe4. If [B]27 ... g5[/B] 28 Ne4 (not 28 h4 gxh4 29 gxh4 Bxh4) and we not only free our bishop but take another pawn in the process: If 28 ... Kf7 29 Bxg5. If 28 ... Bh8 29 Bxg5. If 28 ... either N moves(except Nf3+?) 29 Nxf6+ and 30 Bxg5. If 28 ... Rb6 29 Nxf6+ and 30 Bxg5. Verdict: [B]25 Bf4[/B] and if 25 ... e5 [B]26 dxe5 [/B][B][B]Nxe5[/B] [/B]could be good for us. Backing up, If [B]26 ... Bxe5 27 Bxh6[/B] but we must be careful until we get our N/d1 and R activated. If 27 ... Bf5 28 Rc1 and I think our position holds together long enough for us to get our N/d1 out. (If 28 ... Bd3 29 Nxd3 cxd3 30 Nf2 bxc3 31 bxc3 Rb2 32 Nxd3) Verdict: [B]25 Bf4 e5 [/B](best for Black) [B]26 dxe5 [/B][B]Bxe5 [/B](best for Black) [B]27 Bxh6[/B] gets us a pawn and struggle. - - [B]B) 24 Re1 [/B]is what seems to be the only feasible alternative to [B]24 Rxf6[/B], but it has a weakness. Previously, I wrote: If [B]24 ... bxc3 25 bxc3 R-f5/f7/f8[/B]. But after [B]26 Nxe6[/B] [b]Bxe6 27 Rxe6 Nxd4[/b] I don't like our position. Material and pawn structure is even, whereas after [B]24 Rxf6[/B] we still had threats on Black's weak pawns. - - - My FINAL vote: Rxf6 - 5 points Re1 - 0 points Rc1 - 0 points Bf4 - 0 point Last fiddled with by cheesehead on 2014-03-27 at 03:50

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2014-03-27, 03:54	#24
cheesehead "Richard B. Woods" Aug 2002 Wisconsin USA 2²·3·641 Posts	[QUOTE=cheesehead;369491] Our deadline is [URL="http://mersenneforum.org/showpost.php?p=369483&postcount=134"]Thursday, March 27 12:40 GMT[/URL] [/QUOTE]I've discovered that I seem to have been using "GMT" incorrectly, and that I should've been using "UTC" in its place. GMT starts at noon, not midnight as I've been assuming. UTC starts at midnight.