For danny casolaro. For the lion. And for the future of us all, man and machine alike
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- Navigate this page:
- Large Scale
- Medium Scale
- Small Scale
- SEM - SEmantic Memory
- Evolution
- Partial Understanding: Large Scale to Medium Scale
- Transformability: Small Scale to Medium Scale
- Facilitating Evolvability
- Intertwingling: Difficult, But Important
Ambient Information and SEMThe scope of information was discussed a little, but let's take into consideration what it really means to have a "local" and a "global" system. In general, there are small and large scale systems, and interactions between the two will most likely form a huge part of the transactions that occur on the Semantic Web. Let's define what we mean by large, medium, and small scale systems. Large ScaleAn example of a large scale system is two companies that are undergoing a merger needing to combine their databases. Another example would be search engines compiling results based upon a huge range of data. Large scale Semantic Web systems generally involve large databases, and heavy duty inference rules and processors are required to handle the databases. Medium ScaleMedium scale Semantic Web systems attempt to make sense out of the larger scale Semantic Web systems, or are examples of small scale Semantic Web systems joined together. An example of the former is a company trying to partially understand two large scale invoice formats enough to use them together. An example of the latter is of two address book language groups trying to create a super-address book language. Small ScaleSmall scale Semantic Web systems are less widely discussed. By small scale Semantic Web systems, we mean languages that will be used primarily offline, or piles of data that will only be transferred with a limited scope, perhaps between friends, departments, or even two companies. Sharing data on a local level is a very powerful example of how the Semantic Web can be useful in a myriad of situations. In the next section on evolution we shall be finding out how interactions between the different sized systems will form a key part of the Semantic Web. SEM - SEmantic MemoryThe concept of a SEmantic Memory was first proposed by Seth Russell, who suggested that personal database dumps of RDF that one has collected from the "rest" of the Semantic Web (a kind of Semantic Cloud) would be imperative for maintaining a coherant view of data. For example, a SEM would most likely be partitioned into data which is inherent to the whole Semantic Web (i.e., the schemata for the major languages such as XML RDF, RDF Schema, DAML+OIL, and so on), local data which is important for any Semantic Web applications that may be running (e.g. information about the logic namespace for CWM, which is currently built in), and data that the person has personally been using, is publishing, or that has been otherwise entered into the root context of the SEM. The internal structure of a SEM will most likely go well beyond the usual triples structure of RDF, perhaps as far as quads or even pents. The extra fields are for contexts (an StID), and perhaps sequences. In other words, they are ways of grouping information within the SEM, for easy maintainence and update. For example, it should become simple to just delete any triple that was added into a certain context by removing all triples with that particular StID. A lot of work on the Semantic Web has concentrated on making data stores (i.e. SEMs) interoperable, which is good, but that has lead to less work being conducted on what actually happens within the SEM itself, which is not good, because the representation of quads and pents in RDF is therefore up in the air. Obviously, statements can be modelled as they would be for reification:- rdf:Statement rdfs:subClassOf :Pent . _:s1 rdf:type :Pent . _:s1 rdf:subject :x . _:s1 rdf:predicate :y . _:s1 rdf:object :z . _:s1 :context :p . _:s1 :seq "0" . But clearly a dedicated pentuples format is always going to be more efficient, and aviod the perils of reification:- :x :y :z :p "0" . This language also needs a default context flag that indicates the root context of the document. The root context of a document is the space to which the (non-quoted) assertions are parsed, the conceptual information space in which all of the assertions are taken to be true. Any quoted information in the document (for example, using the Notation3 context syntax) would be in a different (possibly anonymous) context than the root context of the document. TimBL appears, gaguing from the CWM source code, to be using "...#_formula" as the root context for the document, which (if true) is a bit of a nasty hack... what if one creates a property with the same URI? Maintaining interoperability at this level of the Semantic Web is an important thing for the Semantic Web developers to be investigating at this stage. EvolutionA very important concept on the Semantic Web is that of evolution: going from one system into another. Two key parts of evolvability are partial understanding and transformability. We will find out next how these manifest themselves naturally when changing the scale of a system. Partial Understanding: Large Scale to Medium ScaleThe concept of partial understanding is a very important one on the Semantic Web, and can often be found in older documents that came out about the same time as the Semantic Web was first being theorized. An example of partial understanding when moving a large scale system to a medium scale system is of a company trying to make sense out of two invoices, one from Company A and one from Company B. The knowledge that both of the companies use similar fields in their invoices is well known, so company trying to make sense out of the invoices can easily compile a master list of expenditures by simply scraping the data from the two invoice languages. Neither Company A nor Company B need to know that this is going on. Indeed, TimBL included this example in his XML 2000 keynote:- [...] what we'll end up doing in the future is converting things, so for example [...] in the Semantic Web we will have a relationship between two langauges so that if you get an invoice in a langauge you don't understand, and you have... some business software which can pay invoices... by following links across the Semantic Web, your machine will be able to automatically convert it from one language to another, and so process it. - Tim Berners-Lee
Where for example a library of congress schema talks of an "author", and a British Library talks of a "creator", a small bit of RDF would be able to say that for any person x and any resource y, if x is the (LoC) author of y, then x is the (BL) creator of y. This is the sort of rule which solves the evolvability problems. Where would a processor find it? [...] - Semantic Web roadmap, Tim Berners-Lee One possible answer is: third party databases. Very often, it is not practical to have (in TimBL's example) either the LoC or or BL record the fact that two of their fields are the same, so this information will have to be recorded by a reputable third party. One such "third party" that was set up to investigate this is SWAG, the Semantic Web Agreement Group. Co-founded by Seth Russell, Sean B. Palmer, Aaron Swartz, and William Loughborough, the group aims to ensure interoperability on the Semantic Web. They set up what is possibly the first ever third party Semantic Web dictionary, the WebNS SWAG Dictionary.
However, not enough is being done to link information together... in other words, the "Semantic" part of the "Semantic Web" is coming along nicely, but where's the "Web"? People are not using other people's terms effectively; when they use other terms, they often do so because they're aimlessly trying to help, but just generating noice in the process. If you're going to use other people's data, try to find out what the advantage is in doing that beforehand. For example, just because you use the term "dc:title" in your RDF rather than a home brewed ":title", does that mean that suddenly a Dublin Core application is going to be able to "understand" your code? Of course not. What it does mean however is that if the "dc:title" property in your instance is being put to use in such a way that information may be need to repurposed from it in the near future, then you may gain some advantage because "dc:title" is such a commonly used term, you may be able to modify a current rules file, or whatever. Another part of the problem may be due to a problem similar to the one that the early World Wide Web experienced: why bother publishing a Web site when there is no one else's site to link to or be linked to? Why bother publishing a Web site when so few people have browsers? Why bother writing a browser when there are so few Web sites? Some people have to make the leaps for it all to happen, and that's a slow process. What can be done about the situation? Well, it may hopefully sort itself out. Another well-known principle that applies very well to Semantic Web applications is that there is no point in reinventing the wheel; viz., if someone has already invented a schema which contains a comprehensive and well understood and used set of terms that you also need to use in your application, then there is no point in trying to redo the work that they have done. At some points this may lead to a form of "schema war", but survival of the fittest should see to it that a core of the best schemata are put to the most use. This is probably what TimBL means when he says that terms will just "emerge" out of the Semantic Cloud, that when people keep using the term "zip", rather than just recording that my term "zip" is equivalent to your term "zip" which is equivalent to someone else's term "zip", we'll all just use the same URI, and hence interoperability will be vastly improved. Directory: 2013 2013 -> Annual InStructional unit plan 2013 -> The Ministry of Education and Science of Ukraine 2013 -> #1 a lifesafer of virginia inc 2013 -> Name(s): your name here team or Group #(if applicable): Professor’s name 2013 -> Alcott Local School Council (lcs) Meeting Minutes 2013 -> Table Of Contents introduction 2 2013 -> Supplemental demographic information 2013 -> 【Education&Working Experience】 Download 2.1 Mb. Share with your friends:
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