Null move in WinBoard (analysis)

[hgm]

I now posted an experimental WinBoard version that allows the user to play null-move in Analyze Mode. To play a null move, just click on the clock of the side you want to give the move to.

The null move will be stored in the Move History as its SAN form, "pass". This is also what will be saved in PGN files or variations therein, when your game contains a null move, and WinBoard will be able to read it back. You can step past null moves using the arrow keys in the usual way; the engine will be made to follow. You can also start a new variation with a null move, as you start any new variation: by keeping Shift pressed while entering it (= clicking the clock).

The binary can be loaded from http://hgm.nubati.net/WinBoard-TM.zip .
Please let me know if this introduces any undesired behavior.

[slobo]

I now posted an experimental WinBoard version that allows the user to play null-move in Analyze Mode. To play a null move, just click on the clock of the side you want to give the move to.

The null move will be stored in the Move History as its SAN form, "pass". This is also what will be saved in PGN files or variations therein, when your game contains a null move, and WinBoard will be able to read it back. You can step past null moves using the arrow keys in the usual way; the engine will be made to follow. You can also start a new variation with a null move, as you start any new variation: by keeping Shift pressed while entering it (= clicking the clock).

The binary can be loaded from http://hgm.nubati.net/WinBoard-TM.zip .
Please let me know if this introduces any undesired behavior.

Hi, HGM,

It should not be allowed that null move is stored as a principal line of a game. Being used only in analysis, it should be considered only as a variation: it is neither regular nor legal move.

[hgm]

I tend to agree to that, but it is not that obvious how I can enforce it. Even I forbid entering the null move at game level, it would still be possible to 'upgrade' a variation to a game. In fact WinBoard always does that when you open the variation for viewing / editing, so it is not a good idea to forbid upgrading when the variation contains null moves. In fact the variation should already be upgraded before you even can add null moves to it. Whether it will remain a game or be 'downgraded' back to a variation will only be decided later, depending on whether you press Revert/Annotate or not.

So the only thing that could be done is disable saving of a game as PGN when there are null moves in it. But this seems hardly helpful, and in fact very pedantic.

[slobo]

I tend to agree to that, but it is not that obvious how I can enforce it. Even I forbid entering the null move at game level, it would still be possible to 'upgrade' a variation to a game. In fact WinBoard always does that when you open the variation for viewing / editing, so it is not a good idea to forbid upgrading when the variation contains null moves. In fact the variation should already be upgraded before you even can add null moves to it. Whether it will remain a game or be 'downgraded' back to a variation will only be decided later, depending on whether you press Revert/Annotate or not.

So the only thing that could be done is disable saving of a game as PGN when there are null moves in it. But this seems hardly helpful, and in fact very pedantic.

You can use a flag to define a variation: a common one or a null move one.
If a variation is a null move one, you don´t allow it to be promoted (upgraded) to a principal line of a game. This way it also will not be possible to save it in a PGN as a game.

[hgm]

But the problem is that the variation is already promoted even before you can add null moves. There is no way in WinBoard to edit a variation without promoting it first. (It works like ICS examine.)

[Michael Diosi]

Hi,


and you had this idea by yourself.... ? Neat "idea" with the clock

Michael
http://www.playwitharena.com

[Michael Diosi]

Hi,

No ? Maybe you should implement it ? If I look at the software then again maybe not...


Michael
http://www.playwitharena.com

[hgm]

No, it was requested. Originally WinBoard allowed null moves only in games were they are legal.

Clicking the clocks has been the WinBoard way to set the side to move already for decades, but it was not allowed in Analyze Mode so far. So I only had to activate it in this mode as well, in games where null moves are not legal in every mode.

[Michel]

It should not be allowed that null move is stored as a principal line of a game. Being used only in analysis, it should be considered only as a variation: it is neither regular nor legal move.

I think the only restriction should be that one should not be able
to enter a null move in Game Mode (Machine White/Black).

I think it could be allowed in "Edit Game". It makes perfect sense to me to
do a play out in "Two Machines" mode after a null move (to find out who would be better if the side to move did nothing).

Of course this is not really necessary since one can enter "Analyze mode", do the null move there and then enter "Two Machines" mode.

[hgm]

Indeed, there is a good case for allowing null moves also in Edit Game mode. Currently clicking the clock in that mode is used for clock adustment, but this is really an obsolete feature that turned out not to be satisfatory at all. It was more like a work-around to sync clocks in OTB tournaments, but it required switching from Machine White/Black mode to Edit Game to make the adjustment, and then back, which was very inconvenient. In current versions you can adust the clock by Shift+click in Machine White/Black mode, and in Edit Game mode clocks have no significance at all, so there is nothing against using clicks on them to alter the side to move in stead.

It also seems null moves would do little harm in the main line of a game. If the user wants them there, why annoy him by having WinBoard prevent it, if it does not endanger correct operation?