General rules

Tafl rules
Adam
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Re: General rules

Post by Adam » Wed Jan 17, 2018 10:20 am

I think adding the corner rule/trying it out on sea tafl is a good idea as it makes sense with the geography of the game, namely open sea.

I don't think we should implement this rule in historical hnefatafl for two reasons:

Firstly because the game is working so beautifully and is (Finally) in concordance with a historical rule set.

Secondly, the corners are a part of the geography of the tafl board (it could have been round and radial), used by players for strategic and tactical purposes, less so in edge tafl but I would venture the corners affect play. Removing these deadzones will affect the game. Better we see what long term effects such a rule has on sea tafl, or at least run a test tournament.

Regarding Copenhagen, I'm pretty sure we have been over the edge capture idea various times before. The geography of the board allows for the deadzones, creating opportunities to immobilise but not capture the king, forcing black to immobilise, surround or destroy all white soldiers. This makes the deadzone an attractive fallback tactic for white if their opening fails. Conversely a similar fallback tactic for black if the king gets out early and a capture is not possible. An edge square is not an open square, nor is it a throne square, so it has different effects. Otherwise we could take soldiers against the edge. Which I think was the key argument last time we considered this.

Xerxes
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Re: General rules

Post by Xerxes » Thu Jan 18, 2018 11:37 am

I think allowing King capture against the edge in Copenhagen would make a big difference to the game, and so would need some extensive testing (one of the problems with short testing (eg a one-off tournament with a few players) is that it does not allow strategies to develop against a new rule).

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Hagbard
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Re: General rules

Post by Hagbard » Fri Jan 19, 2018 7:40 am

Adam wrote:
Wed Jan 17, 2018 10:20 am
Regarding Copenhagen, I'm pretty sure we have been over the edge capture idea various times before. The geography of the board allows for the deadzones, creating opportunities to immobilise but not capture the king, forcing black to immobilise, surround or destroy all white soldiers. This makes the deadzone an attractive fallback tactic for white if their opening fails. Conversely a similar fallback tactic for black if the king gets out early and a capture is not possible. An edge square is not an open square, nor is it a throne square, so it has different effects. Otherwise we could take soldiers against the edge. Which I think was the key argument last time we considered this.
Xerxes wrote:
Thu Jan 18, 2018 11:37 am
I think allowing King capture against the edge in Copenhagen would make a big difference to the game, and so would need some extensive testing (one of the problems with short testing (eg a one-off tournament with a few players) is that it does not allow strategies to develop against a new rule).

Indeed. The Copenhagen is extensively tested and serves us well, 5000 games now. It is necessary to be very careful about this game.

The Copenhagen is forked into the "Copenhagen unsafe-edge 11x11" for testing. It will take a lot of experience with that one. Perhaps the unsafe edge makes some sense, perhaps it does not work well enough and is discarded, or perhaps it would be another variant for a long time, like Fetlar and Copenhagen are.


Also casshern warned, in private chat:
casshern wrote: 2018-01-11 08:07:18 casshern: Hi, Aage. I read what you wrote about "dead squares" in the large forum and had some thoughts. The ability to capture a piece in a corner in sea battle and HH sounds like a good idea. Although, I like that HH has very few rules and this would complicate its simplicity a bit. Otherwise, it would be nice to be able to capture a piece that is in a corner. Though it is not a common situations, I am not sure how much the new rule will affect the game. If I had it my way, I would just leave the rules as they are with the dead squares. Since, white rarely needs to move a piece to the corner, I only see black moving to a corner and that would benefit white generally.

2018-01-11 08:21:06 casshern: In Copenhagen and Berserk, I would not have the king captured but 3 pieces against an edge. I feel like white is at a disadvantage in both variants, but I feel that way about most variants. Exit forts and shieldwall captures help balance the game, in my opinion, but if the king could be captured by 3 pieces against the edge then black would have an even bigger advantage. Generally, white naturally avoids the king being surrounded by 3 against the edge since that would make him immobile. However, tactically it would benefit white for example if the king was 2 squares from the corner with a black piece blocking the corner. White may still need to move some pawns around to be able to get through, but in the meantime black could move a 3rd piece to surround the king. The new rule would make this a win for black, correct? I don't think it should be that way. I think the game should continue.

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Hagbard
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Re: General rules

Post by Hagbard » Thu Apr 05, 2018 7:27 pm

Adam wrote: I think adding the corner rule/trying it out on sea tafl is a good idea as it makes sense with the geography of the game, namely open sea.

I don't think we should implement this rule in historical hnefatafl for two reasons:

Firstly because the game is working so beautifully and is (Finally) in concordance with a historical rule set.

Secondly, the corners are a part of the geography of the tafl board (it could have been round and radial), used by players for strategic and tactical purposes, less so in edge tafl but I would venture the corners affect play. Removing these deadzones will affect the game. Better we see what long term effects such a rule has on sea tafl, or at least run a test tournament.
casshern wrote: Although, I like that HH has very few rules and this would complicate its simplicity a bit.
...
Though it is not a common situations, I am not sure how much the new rule will affect the game. ... Since, white rarely needs to move a piece to the corner
Ded Fomich wrote: But I think that there is no need to use that new rule about the corner capture because of its rarity. ... I’d prefer to leave HH rules as they are—simple, historical and well working. Maybe this rule can make sense in Sea Battle Tafl.
In all my test games with capturable corner pieces, there were even never pieces in the corners; I suppose it is because pieces tend to move towards the middle of the board or the edges, and not so much towards the corners.

Capture of corner pieces has turned out to be more a philosophical problem ("dead squares"). In reality there've now been played 150 games with this rule in function (both Sea Battle and Hist.) and no corner piece was ever captured at all. Capture of a corner piece turned out to be something which could happen only very very rarely. So the idea is dropped for the Hist. Hnef., and as an experiment kept for the Sea Tafl.

Update Nov. 6th 2018:
There's still not been a single case of corner capture, neither in Sea Tafl, the idea is dropped altogether. It is simpler to remember the rules of variants when only the king type changes (strong king, weak king, unarmed king).

unhandyandy
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Re: General rules

Post by unhandyandy » Sat Dec 29, 2018 6:00 pm

Hagbard wrote:
Mon Feb 13, 2017 2:44 pm
...
The king threatens to exit and a muscovit is moved in between to block. The king then moves to another square and threatens to exit here as well. The same muscovit has to be employed to block this time too. The king moves back to the first square and the muscovit is also moved back to block. When the described moves are repeated a couple of times, he who plays the Swedes must make a different move, because it is he who is the aggressive party.
The "aggressive party" is always trying to break through, to find an open path, somewhere. The reacting player is always busy blocking those paths.

This way of counting repetitions and deciding which player loses the game, is a bit more difficult for the computer, but is very easy to handle for real players.
I'm newbie, so please forgive my ignorance.

This is a reasonable way of handling repetitions: taking a repetition as an admission of failure by one side, and giving the win to the other side. But making the distinction between "aggressive" versus "reactive"(?) player, in addition to the distinction "defensive" versus "attacking", seems a level of abstraction unlikely to have been employed by the medieval players.

I may be quite wrong about that, but my guess is that historically the win was given to the defenders (white), since the attackers have failed to capture the king. Of course the reverse argument can be made, i.e. that the win goes to the attackers because the king failed to escape, but given (1) the systemic advantage of the attackers and (2) the suggestive use of the term "Swedes" for white in this Scandinavian game, I suspect white would have been given the benefit of the doubt.

As for detecting repetitions, I doubt it was much of issue in the historical game: the rule would only be invoked when it became obvious to everybody watching that the position had been repeated because the attacker was unable to make progress.

I assume this has already been discussed somewhere.

nath
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Re: General rules

Post by nath » Mon Jan 14, 2019 1:06 am

Hello unhandyandy,

thanks for sharing your thoughts. I'm not one to argue with the historical part, but I tend to disagree. Not only because the player who choose to end the game prematurely by repetition is basically a coward, which would have been unthinkable between vikings...I think the player who can simply get a repetition is white, not black. White doesn't need to do much to get a repetition. Just tuck your king away somewhere and the repetition is granted.

I do however agree with sqAree (like I said multiple times already) that the draw idea is bad and should be replaced by a loss for white.

Regards
nath

unhandyandy
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Re: General rules

Post by unhandyandy » Wed Jan 16, 2019 4:30 pm

"the player who choose to end the game prematurely by repetition is basically a coward, which would have been unthinkable between vikings"

Interesting point, but after all, white's goal is simply to escape, not defeat black on the field, and escaping is pretty cowardly.

"I think the player who can simply get a repetition is white, not black"

Yes, it's easier for white to get a repetition, so I agree that in modern versions black should be given the win in case of a repetition. My point was that perhaps the historical game wasn't meant to be well balanced.
Last edited by unhandyandy on Thu Jan 23, 2020 5:44 pm, edited 1 time in total.

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Hagbard
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Re: General rules

Post by Hagbard » Sun Nov 24, 2019 11:35 pm

About small boards.
A large board functions as a continuum, the step from a square to its neighbouring square is very small compared to the distance from edge to edge.
Whereas on a small board like the 7x7, a step from a square to its neighbouring square is a very big step.
And so it may happen that some game rule which functions well in the continuum of the large board, breaks down and cease to work in the micro world of the small board.

We've experienced this with the Brandubh 7x7.
The Historical rules of Saami Tablut work on boards from 9x9 and upwards, but fail to work in the same form on the 7x7 board.
On the 7x7 a setup of pieces could not be found, where the king does not too easily exit through the edges, and therefore the king must instead be required to exit through the corners - which corresponds with the found historical Ballinderry board.
However, even the win-in-corner modification of rules turns out to be not enough, measured game balance +1.49. Neither could any changed setup of pieces be found to improve that balance.
The simplest next modification of rules was to modify the capturing of the king in the center of the board, so that on the throne's four neighbouring squares the king is captured by 2 black pieces, same as on rest of the board except on the throne itself (Hat tip: David Zolli, "branan"). This results in a measured game balance of +1.11

The change makes sense - as the board diminishes, so does the throne area, so that this area now includes only the throne itself and not the neighbouring squares, too.

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Hagbard
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Re: General rules

Post by Hagbard » Wed Dec 28, 2022 12:38 pm

Another note on the possible corner capture rule discussed 2018.

Such a rule is actually described for several ancient board games closely related to tafl.
The Roman Ludus Latrunculi is considered to be a predecessor of the tafl games.
The Greek Petteia is considered to be a predecessor of Ludus Latrunculi.

Petteia rules are described here:
https://bead.game/games/traditional/petteia
the rules are immediately recognizable as pure tafl.

Petteia rule 5 says:
5. A BEAD in the corner can be captured when 2 BEADs are placed across the corner.

Very closely related to Petteia is the ancient Japanese board game Hasami Shogi, which is described with the same corner rule:
An enemy piece in a corner cell can be captured by occupying the two cells that orthogonally surround it.
Hasami Shogi is described here:
https://en.wikipedia.org/wiki/Hasami_shogi
which is also recognizable as pure tafl.

However, we found that in tafl the need to capture a corner piece, practically never occurs.

Draganov
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Re: General rules

Post by Draganov » Sat Dec 31, 2022 9:44 am

Hagbard wrote:
Wed Dec 28, 2022 12:38 pm
However, we found that in tafl the need to capture a corner piece, practically never occurs.
I don't agree with this statement. In Sea Battle variants a white piece in the corner could create a lot of troubles for the blacks. In weak king variants a white viking in the corner could also be very dangerous. However, in weak king variants a white piece in the corner is not as dangerous as in Sea Battle.
On the other hand, allowing the blacks to kill a white piece in the corner will make the variant even more in favour of the blacks.

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