Re: [sgf-std] New SGF property: transposition / links
> The SGF file format has succeeded by being a file format. SpecifyingSometimes the GUI or interaction with the user has to be addressed in
> the way a program interacts with a user should be left up the program
the specification. That's the reason why we have a ST property. I am
just trying to find out if someone thinks there may be issues.
> I hope/imagine that most programs will make the presence orI think that depends. When I am editing I'd like to know whether my
> absence of N's and TP's invisible to the user.
change is copied multiple times within the SGF tree or is a local
modification only. Furthermore, when I know that the subtree is copied
(and maybe transformed) I know that I should avoid comments like "upper
right corner" or "B5 should be at C17".
I think idea is good, but there are several problems with initial
proposal that need some resolution:
1. N property
Property N is inteded to be user-visible and editable name for node. So
duplicated exists, and preventing user from giving same node name twice
in file is bad solution.
I think it would be better to define some other property (for example
AC[ int ]), that could be used to reference node in all cases it is
machine referenced. (I have planned such id for other uses, but I would
prefer having single standard one.)
Proposal: define new invisible-to-user property AC[nro] for node, and
use that to reference to node.
I would like to say loops are not allowed, bu:
If we consider following chain of editing
1. create file which contain new properties;
2. edit file with editor that does not know new properties (they
continue to exists a long time).
3. Open file again with editor understanding new properties.
Now at step 3 we may have loops, as at step 2 there is no way new rules
are followed, even though editor was SGF4-compliant.
So I think we should not add new restrictions to what is valid file.
Loops will exists, and programs need to be able to deal with them.
Also nodes with TP might not be leaf nodes anymore.
So in essence new limitations would invalidate SGF4-compliance of
program, which is exactly what standards are supposed to prevent.
Proposal: No new restrictions to SGF4 file structure.
3. Link interpretation
I think we should have 2 types of links:
- Just jump to location, as user would have moved to location (so TP
does not need to be leaf)
- Continue with referenced subtree, as proposed here.
Arno Hollosi wrote:
>> The SGF file format has succeeded by being a file format. Specifying
>> the way a program interacts with a user should be left up the program
> Sometimes the GUI or interaction with the user has to be addressed in
> the specification. That's the reason why we have a ST property. I am
> just trying to find out if someone thinks there may be issues.
>> I hope/imagine that most programs will make the presence or
>> absence of N's and TP's invisible to the user.
> I think that depends. When I am editing I'd like to know whether my
> change is copied multiple times within the SGF tree or is a local
> modification only. Furthermore, when I know that the subtree is copied
> (and maybe transformed) I know that I should avoid comments like "upper
> right corner" or "B5 should be at C17".
> SGF spec: http://www.red-bean.com/sgf/
> Contact: Arno Hollosi <ahollosi@...>Yahoo! Groups Links
> Bill wrote:Not only that, but if the target node is pointed to by more than one
> TP is fine with me, but the requirement that it's target N appear
> before the matching TP is strange. Why have it?
> I tend to agree with Bill. I think that most of us agree that we
> should keep the SGF game tree a directed, non-cylic graph. However,
> as Bill pointed out, as soon as someone reorders variations the
> TP and subtree denoted by N would have to change place as well.
TP, you would have to make sure N comes before all of them.
> That is not exactly easy on programmers either.I guess it depends on what the program does. It wouldn't necessarily
be a problem if the program deals with an expanded tree instead of the
The purpose of TP is to make generation of a file manually with a text
editor a little less tedious. If you have software that can save a
file in SGF format from a game tree generated with a GUI, ***THERE
SHOULD BE NO NEED TO DEAL WITH TP.*** So as far as I can tell, the
problem of reordering a file is based on the assumption that this
reordering is done manually, with a text editor. Just out of
curiosity, what would be gained by doing this?
As was pointed out in another post, GUI issues and file loading and
saving issues should be regarded as independent of each other.
> Michal wrote:Sorry, I missed your point in my earlier post. But I'm not sure what
> when I was making my private sgf extension to solve this, I made
> the Label/Pointer tags but the pointer tag also contained
> information about transformation (axes, colors), so the dictionary
> joseki didn't need to repeat any variations with same logic.
scope you want this extra information to apply to. Does a joseki
dictionary file concern itself entirely with one corner of a 19x19
board? Or are you talking about referring to another corner of the
board which was explored earlier in the same file? If the full-board
positions are not effectively identical by axis/color transformation,
there could be a problem when software tries to evaluate this
position. Joseki battles are of course not independent of each other.
Also, do you generate this dictionary with a GUI or with a text editor?
> ... If we think of it as a macro that actuallyWhether TP is a macro call or a link, these same issues would crop up.
> copies/expands to the subtree denoted by N we "mostly" know how
> to display the result.
> But can we really copy all properties as is? E.g. if
> transformations are allowed (axes, colors) what about comments like
> "in the upper left corner" or annotation properties like GB/GW
> (good for black/white), just to name a few issues.
GB versus GW could be automatically taken care of. You could just
ignore all comments in an copied subtree, or not copy them in the
first place if there is any kind of axis/color change.
> Important issue: what about editing/writing such a file? Suppose IUnder what circumstances would you want to change one subtree but not
> don't want to write the expanded tree, but the compressed macro-
> version. How does the user control whether changing a node affects
> both subtrees (N's and TP's) or only one of them (if the
> display looks exactly the same)?
the other? I'm not asking about axis/color changes here. Why should
the user have this option to make the subtrees of the compressed file
> How do I tell the SGF program to create a new TP orIs this SGF program a text editor or a GUI? If it's a GUI which can
> remove/split/copy the tree denoted by N. I think the GUI issues
> (and therefore the usability of this extension) are not to be
save files in SGF format, why would you want to deal with TP calls?
> The semantics for links, the navigation, display, etc. are muchI don't mean to require programmers to treat TP one way or the other.
> easier for links than for macro-like TP.
The SGF definition should work for any way the programmer wants to use
it. I just used the "macro" analogy as a way of explaining what I was
talking about. Sorry if I wasn't clear about that.
> I'm also interested in the exact semantics of TP with respect toMy proposal is that the positions need not be identical as long as
> ko calculations. If two subtrees have different previous board
> positions (as opposed to the same previous board positions in a
> different order) their children may have different legal moves.
> This is mainly an issue when considering the endgame rather then
> the opening book, of course.
every move, position evaluation, and everything else that gets copied
or linked to is equally valid in both situations. If there are
"irreconcilable differences" then they should be different subtrees.
In a ko situation, and perhaps for the most part in Go, different
battles are arguably not truly independent of each other, because one
usually is more important than the others at any given point. So TP
calls might not be appropriate if the subtree in question is large.
Also I recommend you take a look at my LO proposal (in a separate
thread) for dealing with LOcal battles.
- The big issue I see to resolve is the semantic of the link. I see
several possibilities discussed in the thread, and I'm going to try to
restate the concisely:
The node referenced is the identical position as the node with the
link. Presumably they have the same position *after* each has applied
2) Duplicate Sub-tree
The nodes that follow the referenced node are equally applicable to
the position at this node.
The referenced node should be offered to the user as a possible follow
on to this node. The position at the referenced node could be wholly
Identity seems to have a number difficulties in definition and
- just how "identical" do the positions have to be?
- i.e.: same number of prisoners? or just same delta? passes?
- same comments? markup?
- what about differing in only a tenuki move?
Duplicate Sub-tree has the downside that now each node can no longer
be transformed into a single game position, since the state of the
game will depend on if you took a jump to get there.
Jump gets around these difficulties, but at the expense of being a
different kind of navigation that the existing options.
One way to approach the choice is to look at the use cases and see
which admits the most flexibility. The use cases I see are:
A) Joseki dictionary desire to not replicate whole sub-trees when a
position can be arrived at via two different move sequences. This use
case could be broadened to include color and spacial transposition, or
differing in tenuki.
B) Tsumego. Like joseki, a desire to not replicate whole sub-trees.
Here the game state identity requirement might be more rigorous.
GoProblems.com already does this automatically by identifying
identical positions in the tree: If one has follow on nodes and the
other doesn't -- they are "spliced".
C) General annotation need to have variant lines or main lines
reference other lines within the tree.
It seems to me that the Jump semantic supports all of these. If there
is a need for identical position at both ends, it is easy enough for
the creation tool to enforce that.
The only thing that then needs to be addressed is the intended user
navigation: Is it displayed as an option? Is it followed
automatically? One could support both by this rule: If the LI/TP
property appears as the only property in a node, then the link should
be immediately followed, replacing the game state with the state at
the target node. On the other hand, if there are any other
properties, including just a comment (even an empty comment!), then
the user is offered link as a sort of 'remote variation', and can
choose, as they would choose a variant, to continue in that part of