White 29

[cheesehead]

[QUOTE=cheesehead;374278]
The non-struck ones are:

[B]29 Ne3[/B]
[B]29 Ne5[/B]
[B]29 Nd6+[/B]
[B]29 Na3[/B]
[B]29 Nb2[/B]
[B]29 Nd3[/B]
[B]29 Ne4[/B]
[B]29 Nxe6[/B]
[B]29 Rb1[/B]
[B]29 Bc6+[/B]

and dubious:

? 29 Nxb3 Rxb3 30 Nax5 ????

I think we ought to do some analysis for all these non-struck moves, not just [B]29 Rb1[/B][/QUOTE]Some of those can be struck, too:

[strike]29 Ne3[/strike] Nxc5
[strike]29 Ne5[/strike] Nxc5
[B]29 Nd6+[/B]
[strike]29 Na3[/strike] Nxc5
[strike]29 Nb2[/strike] Nxc5
[B]29 Nd3[/B]
[B]29 Ne4[/B]
[B]29 Nxe6[/B]
[B]29 Rb1[/B]
[strike]29 Bc6+[/strike] Nxc6

[strike]29 Nxb3[/strike] Rxb3 30 Nax5 Ra3 31 Re3 Rxa4 allows Black rook too much action

- - -

That narrows our choices down to:

[B]29 Nd6+[/B]
[B]29 Nd3[/B]
[B]29 Ne4[/B]
[B]29 Nxe6[/B]
[B]29 Rb1

-

[/B]If we're going to avoid losing a piece to the N/b3 fork without moving either of those pieces (N/c5 and B/d2), we have to play something that prevents losing the N/c5 and also does not remove our B/d2's defender.
-

[B]29 Nd6+[/B] is forcing, but removes our B/d2's defender, leaving both our N/c5 and B/d2 [I]en prise[/I]. In order for it to work, we'd have to have enough forcing and/or escape moves to save both the N/c5 and B/d2. But we simply don't have enough of those forcing/escape moves.

(E.g.,
If [B]29 ... Kd8
[/B]If [B]30 Ncb7+ Bxb7 31 Nxb7+ Rxb7 32 Bxb7 Nxd2[/B] we've given two knights for a rook without compensation.
If [B]30 Nxe6+ Bxe6 31 Rxe6 Nxd2[/B] we're down knight-for-pawn without compensation.
If [B]32 Nf7+ Kd7 33 Rd6+ Ke8 34 Rxd2 Kxf7[/B] wouldn't change that.
If [B]32 ... Ke8 33 Nd6+ Kf8[/B] it's still the same.

If[B]29 ... Kf8[/B]
If [B]30 Nxe6+ Bxe6 31 Rxe6 Nxd2[/B] we're, again, an uncompensated piece down.)

So,
[strike]Nd6+[/strike] is unsatisfactory[B].

-
[/B]
We'd previously struck out all B/d2 moves, but let's look at [B]29 Be3[/B] again.

[B]29 Be3[/B] protects the N/c5, but allows [B]29 ... Bxc3[/B]. How bad is that, really?
[B]30 Rb1[/B] threatens to win the Exchange:
[B]30 ... Nxc5 31 Rxb8[/B], but then
[B]... Nxa4[/B] Black gets two pawns plus a knight for his rook.

Instead, [B]30 Rd1[/B] menaces along the open d-file.

If [B]30 ... Nxc5 31 Bxc5[/B] we have threats with
32 Nd6+ (notice that we've skipped a Black move)
If 32 ... Kd8 33 Nf7+
If 33 ... Kc7 34 Bd6+, But, alas, this requires that Black cooperate, rather than playing 33 ... Ke8, or even not passing up his move 31.

I don't see any other better lines -- do either of you guys?
[B]
-

29 Nd3[/B]
[B]

29 Ne4[/B]
[B]

29 Nxe6


[/B][B]29 Rb1[/B]

[LaurV]

[QUOTE=cheesehead;374300]
That narrows our choices down to:
[B]29 Nd6+[/B]
[B]29 Nd3[/B]
[B]29 Ne4[/B]
[B]29 Nxe6[/B]
[B]29 Rb1
[/B][/QUOTE]
I didn't remove Nd6+, because actually we can play Rb1 after it (!). If we play Rb1 before, or after, this is arguable, but Nd6+ is not as bad as the other in the list.

Nd3 is the weakest from there, in my opinion. After Nxd2 Nxd2 Bxc3, we are forced in gote forever (to defend the horses) and all our sente is gone. We need to respond either Rd1 or Re2, and they can continue the attack and keep the advantage pawn. This looks very bad for us.

Ne4 looks a bit better, because now (if we capture with the horse from c) the pawn is defended and they can't really take it. But we still lose all the sente. Moreover, this move blocks the access to b7,a8, so they have an escape for the rook (after move the king) if we play Bf4 later (in case they don't take it, which I really doubt!)

Nxe6, this sounds like a trap, if they beat the bishop, or move the king Kf7, or do other move, they are dead, because we have very heavy artillery there, two horses, a bishop and a rook. In fact we win fast if they fall in this trap. But if they just play "normally", Bxe6, Rxe6 (forced! if we miss, we can't retake the figure anymore) Nxd2 Nxd2 (same, white move is forced) Bxc3, and we must run with the horse back, because if now Nd2c4, they do Rb4, and we lose the side pawn (and maybe the game). So, very complicate, no sente anymore.

What's left in my list is then:

[B]Rb1[/B]
or
[B]Nd6+
[/B]
Now, of course it is arguable which is better, I prefer to keep the horse there, to control the moving of the black rock on the b column.

Therefore I still stay on Rb1 - 5 points.

[cheesehead]

[QUOTE=cheesehead;374278]< snip >

Note:
To our previous [B]29 Rb1[/B] analysis, add:

[B]29 Rb1[/B]

If [B]29 ... Nxc5[/B] [B]30 Rxb8[/B]
If [B]30 ... Nxa4[/B] (threatening 31 ... Nxc3) ????
[/QUOTE]Got it! Forking check plus "Divert the defender"

[B]31 Bc6+[/B] (threatening Bxa4) :-)
If [B]31 ... Nxc6 32 Rxc8+ Kd[/B][B]7 33 Rg8[/B](to encourage ... Bxc3 instead of ... Nxc3). Black's bishop's only safe moves are Bf6 and Bxc3.

We use our rook to capture Black king-side pawns so as to make our g- and h-pawns passed. We use our bishop, knight and rook to keep the a-pawn from advancing beyond a4. While our knight is at c4, Black's king can't get through d6 or b6, unless the N/c6 moves. We have two long-range pieces that can create threats on both sides of the board, while Black has only one.

[cheesehead]

[QUOTE=cheesehead;374346]Got it! Forking check plus "Divert the defender"

[B]31 Bc6+[/B] (threatening Bxa4) :-)
If [B]31 ... Nxc6 32 Rxc8+ Kd[/B][B]7 33 Rg8[/B][/QUOTE]Better here is
[b]33 Ra8[/b] so as to take the a-pawn right away.

[cheesehead]

[QUOTE=LaurV;374317]I didn't remove Nd6+, because actually we can play Rb1 after it (!).[/QUOTE]Hmm...

After [b]29 Nd6+ Kd8 30 Rb1 Kc7[/b] we'd have three pieces [i]en prise[/i], but can rescue all three with:
31 Rxb3 Rxb3 32 Ne8+ Kd8 33 Nxg7 (33 Nxb3 Kxe8 leaves us only even in material) Rb1+ 34 Kf2 Rb2 and our margin is only two pieces for a rook.

[cheesehead]

Yet another branch in the [B]29 Rb1 Nxc5 30 Rxb8[/B] line that I overlooked until now, and it's probably Black's best response on move 30:

[B]30 ... Nd7[/B]

Allows a whole new set of combinations. In some lines we could extend our material advantage from Exchange to whole piece.

If [B]31 Nd6+[/B]
If [B]31 ... Kd8[/B] (not ... Kf8 32 Rxc8+ Nxc8 33 Nxc8 extending our material lead to a whole bishop), our rook is still attacked by the N/d7, so we could do

[B]32 Ra8[/B] (maintaining the pin and double attack on the B/c8).
If [B]32 ... Nb6[/B], then
[B]33 Ra7[/B] (not Ra6 Bxa6 or Rb8 Nd7 inviting draw by repetition)
If [B]33 ... Bf8 [/B] (not 33 ... Be5 34 Nf7+ or 33 ... Nf5 34 Nxf5 or 33 ... N/e7-othermove 34 Bxg7) [B]34 ????[/B]
If [B]33 ... Bf6[/B]
If [B]34 Bb7[/B] (threatening 35 Nxc8 N(either)xc8 36 Nxc8 to clear the 7-rank for our rook)
If [B]34 ... Bxb7 35 Rxb7[/B]
If [B]35 ... Nbd5 36 c4[/B]
If [b]35 ... Nxa4 36 Ne4]/b]
If [B]34 ... Kc7 35 Nxc8[/B]
If [B]35 ... Kb8 36 Rxa5 Kxb7 37 Nxb6 Kxb6 38 Rb5+[/B]
If [b]33 ... h5 34 Bg5[/]
If [b]33 ... g5 34 Nxc8 Nbxc8 35 Ra6/b]
or just
[B]33 Rxa5[/B] and we're up a rook-and-pawn for a knight. (Need to watch out for ... Nc4 fork if we move our N/d6 !)
If [speculation] 33 ... Kd7 34 Nxc8 Nc4 35 Ra7+ Kxc8 36 Rxe7 we're up a rook-and-pawn.

If [B] 31 Ra8[/B] (intending)
If [B] 31 ... ?????[/B]

If [B] 31 ????[/B]

[WMHalsdorf]

[QUOTE=cheesehead;374363]Hmm...

After [b]29 Nd6+ Kd8 30 Rb1 Kc7[/b] we'd have three pieces [i]en prise[/i], but can rescue all three with:
31 Rxb3 Rxb3 32 Ne8+ Kd8 33 Nxg7 (33 Nxb3 Kxe8 leaves us only even in material) Rb1+ 34 Kf2 Rb2 and our margin is only two pieces for a rook.[/QUOTE]

31. Ne8+ wins the black squared Bishop.

[cheesehead]

[QUOTE=cheesehead;374363]Hmm...

After [B]29 Nd6+ Kd8 30 Rb1 Kc7[/B] we'd have three pieces [I]en prise[/I], but can rescue all three with:
31 Rxb3 Rxb3 32 Ne8+ Kd8 33 Nxg7 (33 Nxb3 Kxe8 leaves us only even in material) Rb1+ 34 Kf2 Rb2 and our margin is only two pieces for a rook.[/QUOTE]

[QUOTE=WMHalsdorf;374378]31. Ne8+ wins the black squared Bishop.[/QUOTE]I thought that Black just gets one of our pieces in return, but I didn't look very closely. Hmm...

[B]29 Nd6+ Kd8 30 Rb1 Kc7 31 Ne8+
[/B]
If [B]31 ... Kb6 32 Nxb3[/B]
If [B]32 ... Ka6 33 Nc5+ Ka7 34 Rxa8 Kxc8 36 Nxg7[/B] - we're two pieces up.
If [B]32 ... Ka7 33 Be3+ Ka6 34 Nc7++[/B] mate

If [B]31 ... Kd8 32 Nxg7[/B]
If [B]32 ... Nxc5 33 Rxb8[/B]
If [B]33 ... Nd7 34 Nxe6+ Ke8 35 Ra8 [/B] - we're a rook-and-pawn up.
If [B]32 ... e5 33 Rxb3[/B] - we're two pieces up.
If [B]32 ... ????[/B]

[cheesehead]

[OT]

Test to see whether posts total changes.

A: No. Still 7,290.

I guess I haven't been paying attention.

Or else private subforum posts don't count?

[Xyzzy]

posts in the team forums do not increment your post counter

:mike:

[cheesehead]

Thanks, Mike.

- - -

Here's the accumulation of our so-far analysis for our move 29:

[B](A) 29 Nd6+

[/B]If [B]29 ... Kd8 30 Rb1 Kc7 31 Ne8+[/B]

If [B]31 ... Kb6 32 Nxb3[/B]
If [B]32 ... Ka6 33 Nc5+ Ka7 34 Rxa8 Kxc8 36 Nxg7[/B] - we're two pieces up.
If [B]32 ... Ka7 33 Be3+ Ka6 34 Nc7++[/B] mate

If [B]31 ... Kd8 32 Nxg7[/B]
If [B]32 ... Nxc5 33 Rxb8[/B]
If [B]33 ... Nd7 34 Nxe6+ Ke8 35 Ra8[/B] - we're a rook-and-pawn up.
If [B]32 ... e5 33 Rxb3[/B] - we're two pieces up.
If [B]32 ... ????[/B]

If [b]29 ... Kf8[/b]

If [b]30 ????[/b]

= = = = =

[B](B) 29 Rb1[/B]

+ + +

If [B]29 ... Nxc5 30 Rxb8
[/B]
- -

If [B]30 ... Nd7[/B] (probably Black's best response here)

Allows a whole new set of combinations. In some lines we could extend our material advantage from Exchange to whole piece.

If [B]31 Nd6+[/B]
If [B]31 ... Kd8[/B] (not ... Kf8 32 Rxc8+ Nxc8 33 Nxc8 extending our material lead to a whole bishop), our rook is still attacked by the N/d7, so we could do

[B]32 Ra8[/B] (maintaining the pin and double attack on the B/c8).
If [B]32 ... Nb6

[/B]If [B]33 Ra7[/B] (not Ra6 Bxa6 or Rb8 Nd7 inviting draw by repetition)
If [B]33 ... Bf8[/B] (not 33 ... Be5 34 Nf7+ or 33 ... Nf5 34 Nxf5 or 33 ... N/e7-othermove 34 Bxg7) [B]34 ????[/B]
If [B]33 ... Bf6[/B]
If [B]34 Bb7[/B] (threatening 35 Nxc8 N(either)xc8 36 Nxc8 to clear the 7-rank for our rook)
If [B]34 ... Bxb7 35 Rxb7[/B]
If [B]35 ... Nbd5 36 c4[/B]
If [b]35 ... Nxa4 36 Ne4]/b]
If [B]34 ... Kc7 35 Nxc8[/B]
If [B]35 ... Kb8 36 Rxa5 Kxb7 37 Nxb6 Kxb6 38 Rb5+[/B]
If [B]33 ... h5 34 Bg5[/B]
If [b]33 ... g5 34 Nxc8 Nbxc8 35 Ra6/b]

If [B]33 Rxa5[/B] and we're up a rook-and-pawn for a knight. (Need to watch out for ... Nc4 fork if we move our N/d6 !)
If [speculation] 33 ... Kd7 34 Nxc8 Nc4 35 Ra7+ Kxc8 36 Rxe7 we're up a rook-and-pawn.

If [B]31 Ra8[/B] (intending)
If 31 ... ?????
If [B]31 ????[/B]

- -

If [B]30 ... Nxa4[/B] (threatening ... Nxc3) [B]31 Bc6+[/B] (threatening Bxa4)
If [B]31 ... Nxc6 32 Rxc8+ Kd7[/B]

If [B]33 Ra8[/B] (threatening 34 Nxa5)
If [B]33 ... Nxc3 34 Nxa5 Bd4+ 35 Kg2[/B] we're up a rook for knight-and-pawn

If [B]33 Rg8[/B] (to encourage ... Bxc3 instead of ... Nxc3). Black's bishop's only safe moves are Bf6 and Bxc3. We use our rook to capture Black king-side pawns so as to make our g- and h-pawns passed. We use our bishop, knight and rook to keep the a-pawn from advancing beyond a4. While our knight is at c4, Black's king can't get through d6 or b6, unless the N/c6 moves. We have two long-range pieces that can create threats on both sides of the board, while Black has only one.]

+ + +

If [B]29 ... Nxd2 30 Nd6+[/B] (avoiding ... Nxc4, and preventing ... Rxb1)

- -

If [B]30 ... Kf8 31 Rxb8[/B]
If [B]31 ... Bxc3 32 Nxe6+ Kg8 33 Nxc8[/B] and we're exactly one rook up.
If [B]31 ... ????[/B]

- -

If [B]30 ... Kd8 31 Rxb8[/B]
[speculation]
If 31 ... Kc7 32 Rxc8+
If 32 ... Kxd6 33 Nb7+
If 33 ... Kd7 34 Rc5
If 34 ... Nd5 35 Bxd5 exd5 36 Nxa5
If 36 ... Kd6 37 Rb5 Bxc3 38 Kf2