Is a stone on the 5th row a third row ladder escape? Hex, Havannah

28 replies. Last post: 2016-05-08

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Is a stone on the 5th row a third row ladder escape?
  • wccanard at 2016-04-11

    Hi. I'm new to this forum and to hex in general, but I have read Cameron Browne's book and I am interested in combinatorial game theory in general. Here's (hopefully) a position involving a third row ladder. It's black's move. Who wins with best play?

    I've only just learnt this stuff so may be making mistakes, but my understanding of the position I'm linking to above is that this is a third row ladder, and the question is whether that stone on the 5th row is a 3rd row ladder escape.

    I have essentially no practical play experience but am trying to understand this game properly. Two people on this site have said things which make me believe that it's perhaps “well-known to the experts” who wins in the linked game; my impression is that people who know about this game seem to think that games that look to my novice eye basically equivalent to this one are wins for black.

    However, because of lack of game experience, my current algorithm for answering this sort of question is to look it up on Dr King's site: [[ www.drking.org.uk, Hex templates]](http://www.drking.org.uk/hexagons/hex/templates.html) and I don't see any single-stone ladder escapes up so high. Given that this sort of position has already come up in two of the ten games I'm playing here, I am confused. Are there plenty of templates that are well-known to the experts and useful in practical play and which are not on Dr King's website? Or am I just confused about subtleties in the games I was playing where similar situations occurred.

    In some sense I would rather be able to answer these sorts of questions myself. Does anyone have experience running Benzene on Ubuntu 14.04?

  • wccanard at 2016-04-11

    Many thanks for these lines Loony! I got MoHex to verify that indeed black is connected at the bottom. So there seems to be a standard one-stone-on-the-5th-row ladder template which is not in DrKing's list of templates but which does seem to come up on a 13x13 board.

    My impression is that at this point in my life I need to play through these lines Loony has posted to try and understand the basic principles behind making this sort of connection.

  • HappyHippo at 2016-04-11

    It works for the second and third rows but not the 4th. Also this is why J9 for black (and equivalents) are common opening moves in Hex13

  • Marius Halsor at 2016-04-12

    Wait, wait - wccanard? Are you back? If so, that's great news! Please stay with us :-)

  • wccanard at 2016-04-12

    I'm back temporarily while I learn hex :-)

  • scrampy at 2016-04-26

    @wccannarrd, thanks for getting so many stimulating discussions going!  You mention above “I got MoHex to verify that indeed black is connected” - can I ask how you do this with MoHex ?

  • wccanard at 2016-04-27

    It was a painful experience. I got it running on an Ubuntu 14.04 machine but it took hours of work (although a lot of that time was just spent being stuck and trying to understand error messages). Documentation is limited. It involved editing the source code because of some compatibility issue, and downloading a version of fuego that wasn't too new but wasn't too old either. I would try something, it would fail, and I'd google the error and go on from there. At some point not even this worked and I asked for help in this forum. On the other hand if it were easy there would be more people using it to cheat. I'm afraid I can't remember the details but the other forum thread was ultimately very helpful (someone who had gone through the same pain as me tried to automate the process and did very well; their script did the same source code editing as I'd done but it did a couple of other things I'd not done and these were key).

  • scrampy at 2016-04-27

    I feel your pain, as I went through a lot of the same  a year ago to get Mohex and hexgui to work on Linux Mint x64. It was far from ideal.

    I should have been more specific : how are you able to get Mohex to verify if in a given position a group of pieces and are  “connected”? Is there a function or something that you run after setting up a position?

  • wccanard at 2016-04-27

    Oh! Sorry! The command (if you have the analyze window open) is “DFPN Solve State” and in the console it's  dfpn-solve-state (or dfpn-solve-state w or dfpn-solve-state b if you want to explicitly state whose move it is). Note that sometimes the solver gets a bit confused about whose move it is; if you click on Game->color to move and see what it says there, this might not be what the solver thinks; the solver doesn't seem to update the Game->color to move window. So sometimes I find myself clicking on Game->color to move, seeing it's on “white” and then clicking “white” again; then running DFPN Solve State can sometimes produce a different answer because the solver thought it was black to move but the gui was saying white. As you might well know, the whole set-up takes a little getting used to. Did you find any documentation at all? I've just been clicking on things in the analyse window and then watching the console and figuring stuff out for myself.

  • shalev at 2016-04-28

    Just a quick note: HappyHippo's comment above is wrong; a 5th row stone escapes 4th row ladders (if theres enough empty space on the 5th row). I think it even escapes 5th row and 6th row ladders if theres enough space for Tom's move, but Tom's move isn't needed for the 4th row stone.

  • Bill LeBoeuf ★ at 2016-04-28

    WC I also am happy to have you here. :)

    If you are here to learn Hex I think you will find it takes at least a lifetime. :)

    I believe it the be the the ultimate board game in terms of simplicity of rules versus complexity of play and ideas.

  • wccanard at 2016-04-28

    Yeah I don't want to spend a lifetime learning it, I just want to become a good player. I've heard some people argue that Y is more natural than Hex because the rules are simple, the rules are “better” (both players have the same objective) and that hex is a special case of Y. But there seem to be more people playing hex so hopefully I'll learn from them.

    I also want to do some computer analysis of templates. I find this aspect of the game very interesting. My problem currently is that I'm playing people who know well that this ladder will connect because of that stone, and all I am doing currently is looking up edge templates on Dr King's site and hoping for the best. I have realised that one strategy is to play through all the templates so I can see some standard tricks, and this is what I'm doing.

  • scrampy at 2016-04-28

    The only real “docs” I found related the MoHex and HexGui was this: http://webdocs.cs.ualberta.ca/~hayward/hex/WhatYouNeedToKnow.pdf that has a little section on parameters and engine setup:

    Program, Edit Program: Edit one of the above entries that you have defined. For instance, you can add “ –config wolveSettings.htp” in the command if you do not want to use default settings. At the very least, I recommend turning on the GUI effects for both players and the DFPN solver via “param wolve use guifx 1”, “param mohex use livegfx 1”, and “param dfpn use guifx 1”. Note that any such .htp files must be in your hexguiDir directory.

  • HappyHippo at 2016-05-07

    I only just noticed shalev's comment. My mistake, it looks like a fifth row stone can be used to escape a 4th row ladder. However the commonly played j9 cannot be used because there is not enough space (I think). Unless someone has an answer to this move?

  • Carroll at 2016-05-07

    What about this?

  • David J Bush ★ at 2016-05-07

    BTW the claim that Hex is a special case of Y ignores the swap rule, which may be played only after the first stone is placed, not after both players of a Y game have made a sequence of silly moves. So this “subset game” is Hex without swap.

  • HappyHippo at 2016-05-07

    Carroll: sorry I got lazy there, there should be a row of white stones along the sixth row like in wccanard's example

  • urmaul at 2016-05-07

    From playing MoHex a little, my impression is that g13 works, when we add white stones to block off Black's top and left side walls. And it seems h11 and h12 work too.

  • HappyHippo at 2016-05-07

    urmaul: yes it seems in this situation the best black can play for is to get a second row ladder going the other way, which can be useful in some situations.

  • shalev at 2016-05-08

    Hmm, I didn't realize this before, but yes, Arek is correct. J9 does not escape 4th row ladders. However, it very nearly does: it would escape if either the 2nd row “folded underneath” ladder escapes, or if the “folded on top” ladder escapes. See here. Note that in practice, the folded on top ladder almost always escapes, so this escapes for all practical purposes.

    Still, I never realized this, that's pretty cool.

  • urmaul at 2016-05-08

    Oops. Yeah, Arek is right, both MoHex and me missed that. MoHex usually plays correctly though when I allow it to think 60 instead of 10 seconds. After reducing the available space in the top right, which I don't think changes the result, the solver can easily solve the position, and the result is that f13, h11 and h12 work for white, but g13 doesn't. Black can actually choose between 5 different moves to answer g13. Also, in Carroll's sequence, Black can play differently in the end to win without the folded top ladder.

  • urmaul at 2016-05-08

    I messed up in showing the variant of Carroll's sequence. I meant this.

  • HappyHippo at 2016-05-08

    Thanks for that line Arek. Since j9 is such a popular opening this is good info to have.

  • ypercube at 2016-05-08

    What about (White g13, Black g12)? I can't find a good answer for White.

  • urmaul at 2016-05-08

    (Using the solver) g12 is not among the 5 possible moves. White can answer f13.

  • shalev at 2016-05-08

    I think the simplest counter for black is this one (with this branch in mind). Generally, isolated stones on the first row are pretty much never the unique winning move (counter examples can probably be constructed, but somehow they never show up in actual templates or games).

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