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 2014-06-15, 03:24 #2 cheesehead     "Richard B. Woods" Aug 2002 Wisconsin USA 1E0C16 Posts [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. Last fiddled with by cheesehead on 2014-06-15 at 03:38
 2014-06-16, 16:06 #3 cheesehead     "Richard B. Woods" Aug 2002 Wisconsin USA 22·3·641 Posts 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] ? Last fiddled with by cheesehead on 2014-06-16 at 16:44
 2014-06-16, 17:34 #4 WMHalsdorf     Feb 2005 Bristol, CT 33×19 Posts 31 ... Bxc3 32 Nb5 Bb4 33 Nxe6+Kd7 34 Bh3 may be better.
 2014-06-16, 19:59 #5 cheesehead     "Richard B. Woods" Aug 2002 Wisconsin USA 170148 Posts 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. Last fiddled with by cheesehead on 2014-06-16 at 20:49
 2014-06-16, 22:27 #6 WMHalsdorf     Feb 2005 Bristol, CT 33·19 Posts 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.
 2014-06-17, 10:16 #7 cheesehead     "Richard B. Woods" Aug 2002 Wisconsin USA 1E0C16 Posts 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 Last fiddled with by cheesehead on 2014-06-17 at 10:31
 2014-06-17, 16:22 #8 cheesehead     "Richard B. Woods" Aug 2002 Wisconsin USA 22×3×641 Posts [QUOTE=cheesehead;376012] [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. Last fiddled with by cheesehead on 2014-06-17 at 16:37
 2014-06-17, 16:55 #9 cheesehead     "Richard B. Woods" Aug 2002 Wisconsin USA 11110000011002 Posts 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. Last fiddled with by cheesehead on 2014-06-17 at 17:27
 2014-06-17, 22:03 #10 WMHalsdorf     Feb 2005 Bristol, CT 33×19 Posts This requires an if move since it's a forced move, so why give them what amounts to 2 weeks to make a reply.
 2014-06-18, 00:10 #11 cheesehead     "Richard B. Woods" Aug 2002 Wisconsin USA 22×3×641 Posts 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+ Last fiddled with by cheesehead on 2014-06-18 at 00:14

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