The roles and limitations of the Semantic Web are still unclear. The Semantic Web hopes to provide reliable, cheap, and speedy access to data.

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1 SEMANTIC WEB December 22, 2007 We need a unifying logical language for data - for the machine interfaces to data systems - in the same way that HTML was a unifying language for human interfaces to information systems. Tim Berners-Lee (1955-) INTRODUCTION The Semantic Web, also known as the Data Web and Web 3.0, is really an extension of current Web technology, giving it far greater utility. The goal is to turn the Semantic Web more into a repository of data, than just a collection of Web sites and pages. To do this, it will draw upon data stored online in databases in addition to the text, images, video, and communication the Web contained. The roles and limitations of the Semantic Web are still unclear. DISCUSSION The Semantic Web seeks the grand unification of data. The goal is to bring structured and unstructured data back together, which means evolving from a Web of documents to a Web of data. The Semantic Web hopes to provide reliable, cheap, and speedy access to data. Identification is a key issue with the Semantic Web. Identifiers are all over the place. The semantics of data is paramount. Page 1 of 17

2 The Semantic Web has been described in a sort of touchy-feely way of meeting not only the needs of knowledge sharing but those of socialization and leisure as well. Relations can be established between any data, including documents, photographs, tags, business transactions, etc. Librarians have always been interested in ways of using vocabularies to make connections between documents. The Semantic Web is print dominated. It is like a machine-readable card catalog that ties the Word s documents together in a digital way. The goal is to organize the billions of documents which exist in a way analogous to the Dewey classification system; to turn the existing Web into one big collection of documents rather than many collections of individual Web pages and sites. It is hard to integrate data across a single organization using traditional technology let alone the World. In addition, it takes more than standards to make data innately shareable and available. It appears the W3C is more concerned with creating industry standards than finding workable solutions to existing semantic modeling problems. Their approach tries to fit the problem into a rehashed, failed solution by basing semantic representation on natural language principles. Natural language, e.g. English, has proved to be grossly inadequate when it comes to representing the semantics of data in ways that are amenable to machine processing. All but the smallest semantic models become overly complex and ambiguous. Page 2 of 17

3 Key to the success of Semantic Web Objectives is the use of a common scheme for defining (identifying, classifying, and relating) data, i.e., a Semantic Data Language. There should be one conceptual structure from which everyone works and that structure must be capable of continued revision as new knowledge arises. SECURITY There must be some central control over security on the Semantic Web. It is possible to have different privacy restrictions on the same data depending on the data source, DATA INTEGRATION Data integration has become one of the most important aspects of application development. There has been a shift toward translating data across boundaries. EXISTING PROBLEMS The Semantic Web will inherit all of the problems attached to data integration. Most data fields in existing databases are incompatible and incapable of meaningful translation. In general, data names cannot be used to determine data compatibility, or incompatibility. LABELS The Semantic Web allows people to assign their own data labels instead of trying to agree on industry-wide standards. REASONING The Semantic Web enables users to discover relations among data sources through reasoning. Page 3 of 17

4 FRIEND OF A FRIEND (FOAF) EXAMPLE Friend of a Friend (FOAF) is a decentralized social-networking system based on a special vocabulary created to describe personal information. The FOAF vocabulary can be used to describe the names, ages, locations, jobs, relationships, etc. of individuals. More than onemillion individuals are already interlinked through FOAF files, including users of some isolated, commercial systems like Journal and TypePad. Ref: SEMANTIC DATA LANGUAGE The Semantic Web requires the use of a common semantic language. Semantic Web users are currently developing independent data structures and vocabularies, much like with the history of natural languages. The problem comes in trying to link these disparate data structures and in translating their different vocabulary terms. This can be extremely difficult if the original data structures and vocabulary terms were not created in a unified way. The W3C has adopted the Resource Description Framework (RDF) as its Semantic Web language. RESOURCE DESCRIPTION FRAMEWORK The W3C is pushing the Resource Description Framework (RDF) for building Semantic Web applications. Page 4 of 17

5 The Semantic Web uses the Resource Description Framework (RDF) to make assertions. These assertions are based on triples, where many triples are held in a database. RDF is a fundamental component of the Semantic Web. It is used for defining data and connecting it with Universal Resource Identifiers (URI). RDF names each semantic item and relates it to other items in a way that allows for the automatic interchange of data. Other capabilities can be used to classify, query, and reason about these relations. As would be expected of any semantic language, additional semantic richness can be created by including ontological and taxonomical knowledge. RDF is maturing and more and more applications are being built on it. Some commercial database management systems, e.g., Oracle,.. support RDF. In general, RDF 1) is extremely cumbersome to use, 2) is based on natural language syntax, 3) does not include a common conceptual model, 4) and RDF ASSERTIONS RDF assertions are stated in the form of a triple subject -> predicate -> object Page 5 of 17

6 where the subject is a resource (URI); the predicate is a property (URI); and the object is a resource (URI) or data value (literal). RDF EXAMPLE 1 An example RDF assertion is shown in Figure x. Name Person > John The subject is Person001; the predicate is Name; and the object is John. Figure x The same assertion may be made using the Myers Semantic Data Language is shown in Figures xa and xb. Relation ID Concept Person > Name Instance 001 John Figure xa Concept [0001] Person, instance (data value) 001, is related to concept [0002] Name, instance John, using the identifier-descriptor (ID) concept relation. In this case [0001] and [0002] are Concept Unique Identifiers. OR Relation` Concept Instance Page 6 of 17

7 I 1 [0001] Person 001 I 1 D [0002] Name John Figure xb The difference between RDF and the Myers Semantic Data Language is that RDF treats Name as the relation. In the Myers Semantic Data Language Name is treated as a concept of the same order as Person; the relation (Arc or Edge) is expressed using one of 28 possible syntactic structures, not concept. RDF EXAMPLE 2 Another example RDF assertion is shown in Figure x. Locatedin LosAngeles > CA The subject is LosAngeles; the predicate is Locatedin; and the object is CA. Figure x The same assertion may be made using the Myers Semantic Data Language is shown in Figure xa and xb. Relation I 1 <I 2 Concept [0001] City > [0002] State Instance Los Angeles CA Figure xa Page 7 of 17

8 OR Relation Concept Instance I 1 [0001] City Los Angeles I 1 <I 2 [0002] State CA Figure xb Concept [0001] City, instance (data value) Los Angeles, is related to concept [0002] State, instance CA, using the identifier 1 < identifier 2 (I 1 <I 2 ) concept relation because the < logical operator denotes concept dependency. In this case [0001] and [0002] are Concept Unique Identifiers standing for concepts City and State. Note that instance data in the Myers Semantic Data Language does not have to conform to data processing (no spaces, etc.) conventions, e.g., Loa Angeles vs. LasAngeles. ALTERNATE STRUCTURE The relation can be explicitly included in the concept relation by making it a concept of the same order as City and State as shown in Figure xa and xb. Relation I 1 M 1 <I 2 Concept City > Relation > State Instance Los Angeles located in CA Figure xa OR Page 8 of 17

9 Relation Concept Instance I 1 [0001] City Los Angeles I 1 M 1 [0003] Relation located in I 1 M 2 <1 2 [0002] State CA Figure xb The difference between RDF and the Myers Semantic Data Language is that RDF treats the relation instance locatedin as the relation. In the Myers Semantic Data Language the relation is treated as a concept of the same order as City and State; the relation (Arc or Edge) is expressed using identifier 1 modifier 1 < identifier 2 (I 1 M 1 <I 2,) concept relation which is one of 28 possible syntactic structures, not concept. In this case [0001], [0002], and [0003] are Concept Unique Identifiers standing for concepts City, State, and Relation. WORLD WIDE WEB CONSORTIUM The World Wide Web Consortium (W3C) us an ad hoc organization composed of more than 400 dues paying member companies and universities. The W3C was founded in 1994 to serve as the guardian of foundational Web technology and standards. Important goals include developing foundational Web technologies and advancing related standards, which so far includes XML and RDF. The W3C is co-hosted by the Massachusetts Institute of Technology (MIT), where it is based (USA); the European Consortium for Informatics and Mathematics (France); and Keio University (Japan). TAGGING SYSTEMS A tagging system is Page 9 of 17

10 A number of tagging systems are being used on the current Web, which include del.icio.us; Digg; DOI; My space; and Flickr. These tagging systems are not compatible, even when the same term is used. As a result current tagging systems are not scalable to the degree required for Semantic Web use. ONTOLOGY AND TAXONOMY URI The Semantic Web tries to use Uniform Resource Identifiers (URIs), e.g., the strings beginning with http: or ftp: found on the Web, to identify and connect data in a meaningful way. Anything that has an URI is considered to be on the Web. Probably the biggest problem the Semantic Web has is using a data structure based on natural language. Data structure is that of a triple, a triple, i.e., the subject-predicateobject structure taken from natural language. The triple is the basis of RDF. An article published in the December 2007 issue of Scientific American gives the following example of a RDF triple: Flipper is a Dolphin. It was explained that Flipper is a reference to the relationship Is A that references the concept dolphin, i.e., <uri for Flipper> <uri for Is A> <uri for Dophin>. The problem is with the data structure not the use of the URI. The intent is to agree on, or somehow standardize, triples. The use of the URI to identify and describe a concept creates another major problem. The URI does have value for pointing to existing data located on the Web, its intended Page 10 of 17

11 purpose, but its use for describing semantic structure is a terrible mistake. Any semantic model may use the URI to point to where data resides on the Web but the URS is grossly adequate when it comes to representing meaning. The problem is that data must be defined (identified, classified, and related) in a concise, formal way so that it can be interpreted unambiguously in all situations, such as across domains. How concept relations are specified is of particular importance in that the meaning of concepts is generally context sensitive. The potential impact of the Semantic Web is expanding due to the increasing scale and complexity of data. The current Semantic Web effort has all of the inherent problems associated with past attempts at semantic data modeling, making the expected result a repeat of past failures. A profoundly different approach must be taken if the Semantic Web is to be truly successful. The underlying semantic structure must be based on something new, something like the Myers Semantic Data Language. Every resource on the Semantic Web must be tagged. Work on the Semantic Web is scattered though out thousands of individual projects. It is now possible to crisscross the World via the Web. The semantic web would comprise a phenotypic structure of immense proportion. A fundamental assumption of those currently behind the development of the Semantic Web is that the meaning behind words, i.e., what words refer to, can be discovered and understood by computers. This is a laudable goal, but one much easier said than done, Page 11 of 17

12 especially given that meaning is an innate and biological property of the brain-mind. Before such a computer reality could ever come about, additional knowledge must be gained about how meaning exists within the head, including how it relates to the mysterious phenomena of consciousness. The Semantic Web is a rehash of the current Web with extensions. Simply consolidating data and being able to use it across computer applications does not constitute semantics, especially if the underlying data structure is solely based on natural language principles, of which the RDF triple is a subset. There is little question that the current infrastructure of the Web could be made more amenable to intelligent data manipulation by machines by improving data structure, quality, precision, etc. A lot can be accomplished towards this end without claiming to be semantic, including the automatic collection of data from diverse and disparate sources, data integration, and the interoperability of Web tools. Of special concern should be the impact that data structure, or lack of, has had on the Web. The Semantic Web is a vision that could provide the seeds of important discovery. If properly implemented, the Semantic Web could radically change the way in which we look at and process data, opening up new areas of intellectual and organizational opportunity. There are many hurdles to overcome before the concept the Semantic Web can become a success. One is that the Semantic Web must be based on a unified data structure which does not currently exist in the database technology employed (XML and RDF are not unified data structures). Another is that to integrate data using traditional database technology requires the implementation of numerous data standards across the Web, a virtually impossible task. In short, a different approach should be taken to the Semantic Web Page 12 of 17

13 The goal is to turn the current Web into a vast, decentralized, machine-readable database, providing users direct access to a universe of data. The content of the Semantic Web, unlike the current Web, will be both accessible and comprehensible by computer systems. Progress towards the Semantic Web has been limited. All aforementioned issues are a key to the Semantic Web's success. The underlying assumption that XML and RDF adequately satisfy the semantic needs of the Semantic Web is highly questionable. The Semantic Web will still use the Internet backbone. Data is distributed throughout the world, rather than being consolidated into a few databases. The Semantic Web needs some standard way to address data resources as well as documents. ONTOLOGY Ontology as viewed by the Semantic Web is a set of defined vocabulary terms and the relations among them. OWL Page 13 of 17

14 Owl is an ontology development language that is compatible with and can be understood by RDF. It operates at a higher-order than RDF. The W3C is pushing the use of OWL to make statements about concept classes. OWL makes a distinction between individuals, properties, and classes. SPARQL The Semantic Web has focused on the use of SPARQL for query. SPARQL is a query language that operates with RDF data. INFERENCE ENGINE Inference engines are used to find new relations among vocabulary terms to reveal their meaning. They operate at a higher-order than OWL. The following is a RDF inference. <uri for Flipper> <uri for Is A> <uri for Dophin> <uri for Dolphin> <uri for Subclass Of> <uri for Mammal> <uri for Flipper> <uri for Is A> <uir for Mammal> MARC MARC changed the way in which libraries provided access to intellectual works. It is based on Anglo American Cataloguing Rules (AARC). META-DATA The Semantic Web is trying to use RDF to handle its meta-data. Page 14 of 17

15 WEB-BASED SERVICES WEB SEARCH There are typically three components used for Web searching; crawler, index, and browser. WEB CRAWLER A crawler, aka spider, is used to search for data on a Web page. It is only interested in the text, links, and Uniform Record Locator (URL). The need for a crawler is marginal with structured data. Note: a URL is the equivalent of an address for Web pages. The Metadata SSE does not include a crawler, but it can use the capabilities of such a tool. WEB INDEX Traditional Web search engines use an internal file, or index database, of document data, called an inverted index, to find requested search terms. The index processes the data gathered by the spider software according to various criteria. WEB BROWSER Web browsers provide the interactive, graphical user interface for searching, finding, viewing, and/or managing data, typically over the Web. The traditional browser follows a nonconsecutive way through a set of data, where the data may be directly related or not. The goal is to find the most relevant Web pages (documents) for a user query. The SSE browser is content, not source, oriented. Page 15 of 17

16 Browser software handles requests for data based on the search terms entered. It scans the records created by the index software and orders or ranks the matching documents based on some algorithm. Once documents have been ranked the browser displays the most relevant documents for user selection; the most relevant being typically listed first. Users frequently look only at the top 10 results. The comprehensiveness of the index and the ranking of the documents are key factors in obtaining good query results and crucial to query quality. HYPERLINKS Hyperlinks serve as references providing a way to navigate the Web. Invoking a hyperlink switches the browser window to a different part of the same Web page or to a different Web page altogether. An analysis of the hyperlink (reference) structure provides a queryindependent measure of the quality of a Web page. This is often combined with queryspecific measures such as the frequency of the search terms found in a document. If many hyperlinks point to the same document, its rank is large or highly referenced. MYERS SEMANTIC DATA LANUAGE A key advantage the Myers Semantic Data Language has over the Semantic Web is that it can maintain history across interactions, i.e., has state. Semantic Web transactions, on the other hand, are stateless. SUMMARY It seems wiser to encourage a variety of approaches to the Semantic Web than to put our entire trust and hope into a single approach based on natural language. In addition, adopting premature standards, e.g., RDF, OWL, in areas where the science has not been Page 16 of 17

17 fully worked out could be disastrous. We should resist these premature urges to steer development along an uncertain, narrow path with quite possibility erroneous outcomes. There is no unified theory, or shared meta-theory, for Semantic Web development to follow, nor is there a comprehensive statement of semantic requirements. It is blindly assumed that the semantics of natural language will suffice in spite of its known shortcomings. What every speaker knows is that there are many situations which defy adequate description using natural language. Page 17 of 17