Sometimes, it is hard to find a move that I can absolutely say is a mistake; the worst I can say is "well, I wouldn't have done that"... Robert Irvin's games are usually that way. (Twixt's ineffable judgment calls, apparently, can make the difference between a 1950 and a 2150.) But, by his request, here is a review of his most recent game against David Bush. Yet again, I'm not sure of any outright mistakes; I offer mostly just opinions.
I've noticed that Robert likes using tilts for windmilling, which he does here with |8.j20, and I'm not sure that's wise. On the left side, it's an unlinked peg beneath the diagonal, which looks vulnerable. On the right side, it doesn't catch ladder chases any better than L19; in fact, it seems a little worse, since with L19 you might get |8.l199.s1510.r2011.r1912.s1813.p2014.n2015.n2116.o16, which puts a peg in at o16 that Robert doesn't otherwise have. If everything played out the same way from there, it doesn't seem to make much difference, but it can't hurt. The only question is whether |8.l19 would have been too weak on the left side.
Anyway, the Y rotation continues very well until |10.o5, when David Bush runs out of space. There's only a dim prospect of putting a credible threat down the left side, and definitely no path up the right side. David's |11.g9 might be just a pseudo-windmill, and his Y is really just a line. In any case, Robert can no longer go directly across the top (because of g9) or across the bottom (because of s15), so he does what he has to do: he cuts David's line with |12.o14, creating his own strong linear commitment.
If I were David, I'd be breaking a sweat at this point. This is the end of the opening moves, and Robert seems to have the upper hand. But in Twixt, if the opening moves were well-played, a web of dependencies usually forms, often with some iffy parts, like David's possible threat down the left side. Could it have worked? We'll never know for sure. Or can he fight his way up the right side? Probably not, but it's hard to say. The move he chooses, |13.q11, looks like bullshit to me, but the problem in Twixt is that in the web of dependencies stage, you have to be very careful how you call bullshit on such a move.
What actually followed |13.q11 eventually enabled |17.n14, which would not have worked otherwise: |13.n1414.m1515.p1316.q13, and so that, I have to imagine, is the blunder that David was intending to draw out of Robert, and succeeded.
Moves |18.s1819.p1820.o1821.n1922.p1623.o12 seem to be playing out the inevitable squeezing of Robert's line to oblivion. There are alternate lines, of course, but none of them seem particularly instructive. They all just make it increasingly obvious that Robert's best hope is across the top. If there's anything Robert can actually do to make use of David's N14-Q16 and Q16-bottom gaps as of |17.n14, I don't see it.
Then begins Robert's push across the top. The reason |24.k11 has hope of winning is that if David just gets a little overconfident, stops sitting up straight, and doesn't get quite enough oxygen to his brain, he could blow it just by playing a standard defense: |25.l1126.j927.j1228.h529.j830.j631.l732.m4.
But David didn't disappoint. (Well, everyone except Robert.) Instead of defending his established line, he starts opening up a new line down that iffy left side. That, in my opinion, was the game-winning move. It's not that the left side was in David's favor after all (though maybe it was); it's the fact that David can use the continued threat of connecting to his established line to force Robert into making timid moves that enable bold moves by David to win the left side.
There is, as Robert pointed out to me, an interesting defensive pattern at |29.d12. This peg is effective because either |30.f1231.f11 or |30.f1231.f13 (or |30.c1231.f11 or |30.c1231.f13) form a tilt parallelogram. Either i10 or i14 is essential for this pattern (but having them both is not.) When you first see this pattern, it is very surprising. Even after you've seen it, it is still easy to not see it coming.
On 2008-04-12 at 21:53, Alan Hensel said:
Clarification: "using tilts for windmilling" has nothing to do with Don Quixote :-) "Tilt" = a 3-3 gap, one of the 3 major setups ("beam" (0-4), "tilt" (3-3), "coign" (1-3)). And by "windmill" I mean the defensive moves that proceed clockwise or counterclockwise around the (usually 4) central opening pegs.
I've noticed that Robert likes using tilts for windmilling, which he does here with |8.j20, and I'm not sure that's wise. On the left side, it's an unlinked peg beneath the diagonal, which looks vulnerable. On the right side, it doesn't catch ladder chases any better than L19; in fact, it seems a little worse, since with L19 you might get |8.l19 9.s15 10.r20 11.r19 12.s18 13.p20 14.n20 15.n21 16.o16, which puts a peg in at o16 that Robert doesn't otherwise have. If everything played out the same way from there, it doesn't seem to make much difference, but it can't hurt. The only question is whether |8.l19 would have been too weak on the left side.
Anyway, the Y rotation continues very well until |10.o5, when David Bush runs out of space. There's only a dim prospect of putting a credible threat down the left side, and definitely no path up the right side. David's |11.g9 might be just a pseudo-windmill, and his Y is really just a line. In any case, Robert can no longer go directly across the top (because of g9) or across the bottom (because of s15), so he does what he has to do: he cuts David's line with |12.o14, creating his own strong linear commitment.
If I were David, I'd be breaking a sweat at this point. This is the end of the opening moves, and Robert seems to have the upper hand. But in Twixt, if the opening moves were well-played, a web of dependencies usually forms, often with some iffy parts, like David's possible threat down the left side. Could it have worked? We'll never know for sure. Or can he fight his way up the right side? Probably not, but it's hard to say. The move he chooses, |13.q11, looks like bullshit to me, but the problem in Twixt is that in the web of dependencies stage, you have to be very careful how you call bullshit on such a move.
Maybe |14.q13 15.s12 16.p11 17.??? With Robert's potent threats of R10, S5 and the 0-3 gap at that point, is there a good reply here for David? How about after |14.q13 15.s12 16.p11 17.t6 18.u10? It's a fight.
What actually followed |13.q11 eventually enabled |17.n14, which would not have worked otherwise: |13.n14 14.m15 15.p13 16.q13, and so that, I have to imagine, is the blunder that David was intending to draw out of Robert, and succeeded.
Moves |18.s18 19.p18 20.o18 21.n19 22.p16 23.o12 seem to be playing out the inevitable squeezing of Robert's line to oblivion. There are alternate lines, of course, but none of them seem particularly instructive. They all just make it increasingly obvious that Robert's best hope is across the top. If there's anything Robert can actually do to make use of David's N14-Q16 and Q16-bottom gaps as of |17.n14, I don't see it.
Then begins Robert's push across the top. The reason |24.k11 has hope of winning is that if David just gets a little overconfident, stops sitting up straight, and doesn't get quite enough oxygen to his brain, he could blow it just by playing a standard defense: |25.l11 26.j9 27.j12 28.h5 29.j8 30.j6 31.l7 32.m4.
But David didn't disappoint. (Well, everyone except Robert.) Instead of defending his established line, he starts opening up a new line down that iffy left side. That, in my opinion, was the game-winning move. It's not that the left side was in David's favor after all (though maybe it was); it's the fact that David can use the continued threat of connecting to his established line to force Robert into making timid moves that enable bold moves by David to win the left side.
There is, as Robert pointed out to me, an interesting defensive pattern at |29.d12. This peg is effective because either |30.f12 31.f11 or |30.f12 31.f13 (or |30.c12 31.f11 or |30.c12 31.f13) form a tilt parallelogram. Either i10 or i14 is essential for this pattern (but having them both is not.) When you first see this pattern, it is very surprising. Even after you've seen it, it is still easy to not see it coming.