Duo to the Death

Blokus has taken over my life

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?


4 Responses to “XF Rubik, two lines of defence”

  1. Gerenuk said

    Hmm, so in general violet’s possible moves are P, W or N on the right and W or I5 on the left.

    For both variants I5 left is possible. One option to think about is orange aggressive L on the right, which is vulnerable, but so is I5.

    The problem with circling can be the right area is large but a total of 6 points or so. So unless orange finds a circling advantage, he is forced to mirror circling and end up with the smaller left area. Not to speak of the circling trouble due to existing corners.

    For variant 1, violet could try to circle one step on the right (maybe W?), then block left and exploit the leak.
    Or violet could even try to move right with N, we he isn’t scared of a whacky orange L kiss on the left.

    More defenses to try are ones where orange is less greedy with the 2nd move on the left. Violet’s move on the right doesn’t go far beyond the X. So orange could try many different more defensive moves on the left as 2nd move, planning to continue just as far on the left as violet will be able to with P on the right. The only disadvantage is some taken up space by these more defensive moves.

    Probably best to get a blokus board and try out the circling lines 🙂

  2. Gerenuk said

    OK, by testing we concluded that aggressive L fails to it’s weak 4-2 side. Violet only has to circle and exploit this. The violet I5 doesn’t have that 2 leak so it can be blocked easier.

    Anyway, here is the defensive moves I meant. Maybe someone has a similar idea.
    One option is W(G6ldld) (or Z4?) followed by F(F8llu). This mirrors a possible violet P circle and leaves some chunky W which might hamper violet circling if he gets that far. If he doesn’t, then the 1-2 leak in the center might give orange a little advantage. I remember losing with this to Mike, but I tried that only once. Maybe it can be improved. Ideas?

    • nd said

      The leak in the centre would be useless because if orange continues circling then the leak is obliterated; & orange must continue circling. Catch-22.

      • Gerenuk said

        The plan is, that if violet choses to circle he will get stuck at the W or whatever defensive move orange put there. The leak is only for the case that violet wants to reverse.

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