Opening puzzle: does the first player lose? TWIXT PP

13 replies. Last post: 2004-09-17

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Opening puzzle: does the first player lose?
  • David J Bush ★ at 2004-09-08

    Philippe Van Schendel, who created the K2z server, sent me an interesting puzzle. Suppose the board is just 12x12 instead of 24x24. Suppose also, the pie rule (swap rule) is not used. On such a small board, one would expect the advantage of the first move to be absolutely crushing. For example, after 1.F7

    1.F7

    The first player seems to have total domination. But what if the second player answers with 2.F5?

    1.F7 F5

    How should the first player proceed here?

    For example, if 3.F3 E7*

    1.F7 F5 F3 E7*

    or if 3.H5 H9

    1.F7 F5 H5 H9

    or if 3.J5 I3

    1.F7 F5 J5 I3

    Where is the crack in the second player’s armor? Or is there none? Does the first player lose here?

    Feel free to discuss variations. I have worked out an answer, but I will wait a while before I post it.

    I should mention that I discussed this opening on the MSO website. I looked at 1.G6 G8 which is rotationally symmetric. Using the same coordinates as I am using here, I said that after 1.F7 F5 J5 is a strong move. But I didn’t consider 4.I3!

  • na_wspak at 2004-09-08

    what about 3.h5?

  • Alan Hensel at 2004-09-08

    na_wspak: did you mean 3.i5? (David already covered 3.h5.)

    I think I would not start with 1.f7. The 6/7 row is fine, but the f/g columns allow a balanced response. Did you try 1.e7?

    I don’t have time to do any more analysis on this – I’m leaving for 4 days and will be back on Sunday night (Sep 12).

  • Philippe Van Schendel at 2004-09-09

    David has found an exciting line:

    F7,F5,H5,H9,D8,G3,F6,E7,J4,G6,H6,I5,I6,G7,J9,L9,K7,J10,I8

    D8 is a strong move

  • David J Bush ★ at 2004-09-09

    Alan, you said: "I think I would not start with 1.f7. The 6/7 row is fine, but the f/g columns allow a balanced response. Did you try 1.e7?"

    My question was not about 1.E7. Of course 1.E7 wins. My question was, what is the correct response to 1.F7 2.F5. All my references to “does the first player lose here” have to do with this particular opening. That’s what “here” means. Do you believe 1.F7 loses?

    na_wspak, I showed a diagram after 1.F7 2.F5 3.H5 4.H9 do you see it? That does not mean that I actually “covered 3.H5,” but it does mean that if you are going to claim 3.H5 wins, you should provide a response to 4.H9.

    As Philippe points out, one answer to 4.H9 is 5.D8*

    F7 F5 H5 H9 D8*

    Now if blue tries 6.G7** orange can play D4

    F7 F5 H5 H9 D8* G7** D4

    Or if 6.G3* then 7.F6* wins:

    F7 F5 H5 H9 D8* G3* F6*

    One possible continuation is 8.E7* 9.J4* 10.G6* 11.H6* 12.i5* 13.i6* 14.G7* 15.J9 16.L9 17.K7** 18.J10** 19.i8**

    finalpos

    What really surprised me was the variation 1.F7 2.F5 3.J5 4.i3! which I cannot find an answer to. See my first post for a diagram of that position.

  • David J Bush ★ at 2004-09-09

    Oops sorry, the final diagram should look like this:

    finalpos

  • Philippe Van Schendel at 2004-09-10


    Technolion has found another variation against my bot:

    1: F7 F5
    2: H5 H8 !!!

    3: D6 is the best move i’ve found, it lead to a draw, i cannot find a clear win

    see diagram:

    F7F5H5H8

  • Philippe Van Schendel at 2004-09-10


    oops the html tag did not work.

    you can check at www.k2z.org/images/F7F5H5H8.PNG

  • Philippe Van Schendel at 2004-09-10


    sorry to polluate this topic: last try:

    F7F5H5H8

  • David J Bush ★ at 2004-09-11

    Philippe, this time I will not tell you right away my answer to F7 F5 H5 H8. Let Alan and the others work on it.

    Also, please use the same numbering system for the moves that was used at the start of the thread. The first player makes odd-numbered moves and the second player makes even-numbered moves.

    For those who have not used the K2z server, you might like to know that the board doesn’t have to look like Philippe’s image. The user can make the “graph paper” lines disappear, as well as the diagonal lines, if desired. The colors of the pieces can be adjusted also.

  • David J Bush ★ at 2004-09-16

    I guess five days is long enough...

    I don’t see how the 2nd player can achieve a draw after 1.F7 F5 H5 H8 i7*. For example 6.i10* D6*



    There are many branches, but they all look like direct wins for the first player. What did I miss?

  • na_wspak at 2004-09-17

    im not a good twixt analiser so sorry if i dont see obvious things but what if 2nd player moves 8.f9? if 9.c9 then 10.9 if 9.b9 then 10.c11 did i miss sth?

  • na_wspak at 2004-09-17

    ah sorry saw it just after i had sent the message. of course 9.d10 is the solution...

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