Duo to the Death

Blokus has taken over my life

Archive for the ‘XF Rubik’ Category

XF Rubik, two lines of defence

Posted by nand on April 6, 2010

XF Rubik is one of the two most frustrating openings to play against (the other being XF Lerpy) since (1) there are some well-mapped lines that violet can play automatically to win by a good-to-excellent margin and (2) it’s not obvious what to do to make the loss at least up-for-grabs rather than inevitable if violet is at least moderately competent (or has a memory stocked with the more common lines). Anyway, here are two lines of defence that I think were examined a year or two ago, discarded, but have been revived. Like most old/new lines they may be flawed but since the exact reasons why they are flawed are now forgotten (or were worked out by players who are no longer frequenters of the site) and since blokus strategy has gotten subtler over the years, they are definitely worth a second look. At the moment they’re having a lot of success on the site but… well, now I’ve written a post I’m expecting that they will get a little less successful.

Variant 1:

Variant 2:

The bottom one looks better, since the 1-2 series of holes created to the left of orange F is something one instinctively avoids in duo. Yet the first one does force violet to play the ugly I5 on left if he wants to stretch past it. The good thing about both of these ones is that violet F is easily cut off & so violet is tempted to defend on right on move 3, & if that occurs orange has a lot of strong moves on the left (probably Y or L5), & I think the game is orange’s to win then. But I think the circling game doesn’t look great for orange: here’s a line that works with either positioning of orange F:

(Note that if orange plans to block on the bottom on turn 4, then orange Y should probably be L5 or even a kiss move like T4 or T5. But that looks kinda suicidal to me.) Anyway, so violet’s got two perfect series of jaggies for orange to climb over, & meanwhile violet has lots of nice moves on either side: Z5 or W on bottom, L5 kiss or hang on top. Am I missing something or is this a writeoff?

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Posted in openings, XF Rubik | 4 Comments »

Studies in XF Rubik #2

Posted by nand on July 8, 2009

I wasn’t entirely happy with my solution to this in the previous post (a 2-point loss for orange), though that line has the advantage of being more or less a forced game: if orange wishes to lose by only 2 points, violet really has to go along & can’t win by any more. Very useful for tournament play.

BUT: I’m not happy with that orange T5 kiss move, since it seems to me obvious that (1) it’s an unnecessary bit of finesse (since violet will not block that corner immediately) and (2) since it’s a close game & violet is really starved for spots for the 1 and i2 pieces, it’s foolish to give him those spots for free.

So, consider these screenshots as part of my continued exploration of this game, diverging at the point where I played T5 in the earlier game. I won’t give blow-by-blow lists of moves, as it’s getting late in the evening & they are mostly obvious (especially since the opening moves are identical to Study in XF Rubik #1), but I will provide comments.

XF Rubik study 2.1

One-point win for orange. Moves from L5-F on: I4-N / T4-L5 / N-I4 / V5-I3 and the rest is packing. Violet N is bad as it’s the only good block for the top — the V5 leaves an I3 hole, enough for orange to eke out a win.

XF Rubik study 2.2

I realized that the orange N in the previous game is the wrong way round, as orange needs to threaten to grab I3 AND i2 on top. So this line shows that violet can get a 3-point win this way. (If orange N is turned the right way then it’s a 2-point win for violet… I haven’t got a screen cap, but will post it later.)

XF Rubik study 2.3

So here’s another variant on the first game, with orange N in the “right” position, & orange deciding to stop the I5 (which I think is a mistake…. orange has a nice i2-1-I4 series off violet I5, & violet can’t make a really big block in bottom right off the I5 anyway). 3-point loss for orange.

XF Rubik study 2.4

A big win for orange if violet continues to circle. Violet Z5 is a mistake–should be Z4 (1 less point for violet, 2 less for orange) but anyway, this is not good for violet — the leak off the violet L5 isn’t enough to do much of anything.

XF Rubik study 2.5

This time I used L5 not F, & the results are interesting (though I have to see what it’d be like if violet blocked in top right rather than playing I4. A close win for orange, even despite the space-eating I5. (I would have to check if blocking the I5 move with P or Z4 and letting violet get I3 on top is better for orange.)

The moves from L5 on: L5-L5 / I4-T4 / T4-N / N-I3 / I5-V5 / the rest is packing.

OK, so take it from here, folks…. I want to know where these games can be improved from either side.

Posted in openings, XF Rubik | 2 Comments »

Studies in XF Rubik #1

Posted by nand on June 2, 2009

This is one of the most boring, because most effective, of openings: violet can usually win, though not usually by a lot if orange knows the lines. It’s often referred to as the Rubik after Rubik87, a player who spent a lot of time working this one out (with me frequently as orange!). — Anyway, here’s one line.

I think this is perfect play on both sides... improvements welcome

Violet 65 - Orange 63. I think this is perfect (but cautious) play on both sides... improvements welcome


Moves:

1. X – X
2. F – W
3. Y – Y
4. P – I5
5. L5 – T5
6. I4 – L5
7. T4 – O4
8. I5 – P and the rest is packing

[I originally misordered the moves, hence Rubik’s comment on I3 below: the above is the correct version]

Note that it is essential that orange play W, not F or Z5 (or W flipped around). Otherwise violet is not forced to play I4 to prevent the potential leak off W — instead he can play U, & the packing favours violet by a wide margin.

The main variants here come with violet’s P, which is also sometimes W (hanging) or N (kissing). I’ll post more about these later.

The great thing about this line, by the way, is that as far as I can see violet’s moves are virtually all forced, with the exception of the P. Once the P is played, there is nothing violet can do. A 2-point win is still a win, but it’s so small (given that violet has a huge advantage by going first) that most experienced players consider it a tie.

Posted in openings, XF Rubik | Tagged: | 5 Comments »