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Subject: RE: [xtm-wg] parallel development of syntax and concept models
Jim Farrugia wrote: > JIM ALSO COMMENTS AND ASKS ... > > 5) There seem to be two particular ways to talk about just what > a topic is: one is the familiar refrain that a topic > must have at > least one of the following: a name, an occurrence, or a role played in > association with another topic. The other is the notion that a topic is > in some sense both > a "node" and a "link" between nodes, which is what > Michel and Ben > seemed > to be suggesting today in their responses to my original > questions. > (Below I refer to the former as "the first way" of understanding > what a topic is, and to the latter as "the second way" ....) I > think it > is worthwhile to keep these two ways of understanding a topic in mind, > and perhaps come up with an elegant synthesis of these two ways of > looking at things. Just a thought. > It is also worth considering topic as binding point - an addressable object which is assigned properties. > 6) Is it fair to say that, in some sense, the topic link > element form > is, informally speaking, the abstract box that houses > only one of > the three pieces that make up a topic (in the sense of the > first way of > understanding mentioned above)? Specifically, one can find a > topic name > in the topic link element form. > 'In' ? Perhaps not. 'Attached to' or 'Associated with' might be a better way of visualising it. > 7) Also, in considering the dual nature of topic as both > node and > link, > (the second way of understanding what a topic is), is it fair to > say that the topic link element form, by itself, deals with only the > notion of "topic as node", and that it deals with this via > the topic id > or name ? That is, > within the topic link element form, there is no mention > of linking > (between topics and topics or between topics and > occurrences). Instead, > the two ways to think of "topic as link" are actually specified > elsewhere. > Specifically, the link that connects topics with topics is > specified in the association link element form, and the link that > connects topics with occurrences is specified within the topic > occurrence > architectural form. Is this accurate? If so, it helps explain > why this > seems confusing (that there is no linking done or specified within the > topic link element form). > The topic link should be considered to be an aggregating link of topic occurrences. In the Hytime syntax of 13250, this is explicit - the topic link element <topic> is an varlink architectural element, if the topic has occurrences. The link then consists of a number of anchors (the occurrences), each of which point to one or more resources. In other words, the spec uses 'link' to mean a collection of anchors - I think that you are thinking of link as an individual anchor and that is causing some confusion. > 8) And so, in summarizing these last thoughts, we can > consider a topic > either as being made up of at least one of name, > occurrence, role > played .... or as a "node/link" duality. When we look in the spec at > the topic link element form, we can see just one piece of each of > these ways of understanding topic: we can see the (optional) name > in the first way of understanding, or we can see, say, the > topic id > as representing the node in the node/link way of understanding > topic. But we can't see, *in the topic link element form itself* > any of these other pieces of these two ways of understanding. > Specifically, in the first way of understanding, we don't find > in the topic link element form any mention of "topic as occurrence > or role played ..."; and in the second way of understanding, we > don't find the notion > of topic as link. To complete the picture of both > understandings we > need to look outside the topic link element form itself. > Is all this > accurate? > If I understand correctly, the 'first way' of understanding a topic is as an object with some characteristics. The 'second way' of understanding is as a link which can be addressed (i.e. can be the target of another link). It is important to not try and look for all of the aspects of the model in the 13250 syntax. There are aspects of the model that are implicit. For example, there is no syntactic link from a topic to the association for which it defines one role or from a topic to the topic for which it defines a type. This is a syntactic constraint, because maintaining redundant back pointers is hard. However, there is a specific syntactic construct that links an association role to the topic that describes it or a topic to its type (as described by another topic) - the back-pointer is 'implicit' in the syntax. > 9) The notion of "topic as link" in the "node/link" duality way > of understanding topics, seems to be partly dealt with > in the topic occurrence [element form?]. It is here where one > kind of link is treated - the link between a topic and > its occurrence. > This same topic occurrence [element form] seems also to > deal with the second of the three pieces (i.e., > occurrence) in the > first way of understanding a topic - that a topic consists of a > name, an occurrence, or a role played ..... Is this accurate? > Again, the occurence is an anchor, and as such could be considered to be part of the link. > 10) The rest of the "topic as link" in the "node/link" > duality way > of understanding topics, seems to be dealt with in the > association link element form. (I have some questions about > just how such a link is established between topics using this > form, but ...) > > What is still dangling for me is the missing piece of > "role played in association with other topics" in the first way > of understanding what a topic is. > > 11) What is the key insight behind the association role > that makes > it, in the first way of understanding what a topic is, such a key > component? And how does an association role relate to the > "node/link" way of understanding topics, if at all? Think of it like this: If a topic has neither name, nor occurrence, and it is not part of an association link with another topic, what is its purpose ? (typing and scoping can be defined as associations). So at least one of those three things is required for a topic to be meaningful (and probably more than one of those things is required for it to be useful). Cheers, Kal -------------------------- eGroups Sponsor -------------------------~-~> Thousands of Great Jobs, One Great Location! Austinatwork.com. Great Jobs, Great Life! http://click.egroups.com/1/7847/4/_/337252/_/967543031/ ---------------------------------------------------------------------_-> To Post a message, send it to: xtm-wg@eGroups.com To Unsubscribe, send a blank message to: xtm-wg-unsubscribe@eGroups.com
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