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Re: [sgf-std] New SGF property: transposition / links

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  • Arno Hollosi
    ... 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
    Message 1 of 12 , Jul 30, 2008
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      > 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
      > author.

      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".

      /Arno
    • Lauri Paatero
      Hi, 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
      Message 2 of 12 , Jul 30, 2008
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        Hi,

        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.

        2. Loops

        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.

        t.
        Lauri Paatero


        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
        >> author.
        >>
        >
        > 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".
        >
        > /Arno
        >
        > ------------------------------------
        >
        > SGF spec: http://www.red-bean.com/sgf/
        > Contact: Arno Hollosi <ahollosi@...>Yahoo! Groups Links
        >
        >
        >
        >
        >
      • David Bush
        ... Not only that, but if the target node is pointed to by more than one TP, you would have to make sure N comes before all of them. ... I guess it depends on
        Message 3 of 12 , Jul 30, 2008
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          > Bill wrote:
          > 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.

          Not only that, but if the target node is pointed to by more than one
          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
          compressed file.

          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:
          > 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.

          Sorry, I missed your point in my earlier post. But I'm not sure what
          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 actually
          > 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.

          Whether TP is a macro call or a link, these same issues would crop up.
          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 I
          > 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)?

          Under what circumstances would you want to change one subtree but not
          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
          different?

          > How do I tell the SGF program to create a new TP[] or
          > remove/split/copy the tree denoted by N[]. I think the GUI issues
          > (and therefore the usability of this extension) are not to be
          > underestimated.

          Is this SGF program a text editor or a GUI? If it's a GUI which can
          save files in SGF format, why would you want to deal with TP calls?

          > The semantics for links, the navigation, display, etc. are much
          > easier for links than for macro-like TP[].

          I don't mean to require programmers to treat TP one way or the other.
          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.

          syeates said:
          > I'm also interested in the exact semantics of TP[] with respect to
          > 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.

          My proposal is that the positions need not be identical as long as
          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.
        • Mark Lentczner
          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
          Message 4 of 12 , Jul 30, 2008
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            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:

            1) Identity
            The node referenced is the identical position as the node with the
            link. Presumably they have the same position *after* each has applied
            any moves.

            2) Duplicate Sub-tree
            The nodes that follow the referenced node are equally applicable to
            the position at this node.

            3) Jump
            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
            different.

            Identity seems to have a number difficulties in definition and
            resiliency:
            - 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
            the tree.

            - Mark
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