Where are the Semantics in the Semantic Web 1 Introduction The current evolution of the Web can be characterized from various perspectives Jasper Uschold 20011 Locating Resources: The way people find things on the Web is evolving from simple free text and keyword search to more sophisticated semantic techniques both for search and navigation Users: Web resources are evolving from being primarily intended for human consumption to being intended for use both by humans and machines Web Tasks and Services: The Web is evolving from being primarily a place to find things to being a place to do things as well [Smith 20011 All of these new capabilities for the Web depend in a fundamental way on the idea of semantics. This gives rise to a fourth perspective along which the Web evolution may be viewed Semantics-The Web is evolving from containing information resources that have little or no explicit semantics to having a rich semantic infrastructure Despite the widespread use of the term"Semantic Web, it does not yet exist except in isolated environments, mainly in research labs. In the w3C Semantic Web Activity Statement we are told that he Semantic Web is a vision: the idea of having data on the Web defined and linked in a way that it can be used by machines not just for display purposes, but for automation, integration and reuse of data across various applications [W3C 2001][emphasis mine] As envisioned by Tim Berners-Lee The Semantic Web is an extension of the current Web in which information is given well-defined mean better enabling computers and people to work in cooperation. [Berners-Lee et al 2001][emphasis min [ SOmething has semantics when it can be processed and understood by a computer, such as how a bill can be processed by a package such as Quicken. " [Trippe 2001 There is no widespread agreement on exactly what the Semantic Web is, nor exactly what it is for. From the above descriptions, there is clear emphasis on the information content of the Web being machine usable and associated with Note that"machine" refers to computers(or computer programs)that perform tasks on the Web. These programs are commonly referred to as software agents, or sofbots and are found in Web applications Machine usable content presumes that the machine knows what to do with information on the Web. One way for this to happen is for the machine to read and process a machine-sensible specification of the semantics of the information. This is a robust and very challenging approach, and largely beyond the current state of the art. A much simpler alternative is for the human Web application developers to hardwire the knowledge into the software so that when the machine runs the software. it does the correct hing with the information. In this second situation, machines already use information on the Web. There are electronic broker agents in routine use that make use of the meaning associated with Web content words Ich as"price, weight, destination, and"airport, to name a few. Armed with a built-in with the lowest price for a book or the lowest air fare between two given cities. So, we still lack an Sites understanding of these terms, these so-called shopping agents automatically peruse the Web to find adequate characterization of what distinguishes the future Semantic Web from what exists today Because RDF (Resource Description Framework) [w3C 1999] is hailed by the w3C as a Semantic Web language, some people seem to have the view that if an application uses rdf, then it is a Semantic Web application. This is reminiscent of the "If it is programmed in Lisp or Prolog, then it must be Ar"sentiment Final Draft Submitted to AI MagazineWhere are the Semantics in the Semantic Web Final Draft Submitted to AI Magazine Page 2 1 Introduction The current evolution of the Web can be characterized from various perspectives [Jasper & Uschold 2001]: Locating Resources: The way people find things on the Web is evolving from simple free text and keyword search to more sophisticated semantic techniques both for search and navigation. Users: Web resources are evolving from being primarily intended for human consumption to being intended for use both by humans and machines . Web Tasks and Services: The Web is evolving from being primarily a place to find things to being a place to do things as well [Smith 2001]. All of these new capabilities for the Web depend in a fundamental way on the idea of semantics. This gives rise to a fourth perspective along which the Web evolution may be viewed: • Semantics—The Web is evolving from containing information resources that have little or no explicit semantics to having a rich semantic infrastructure. Despite the widespread use of the term “Semantic Web,” it does not yet exist except in isolated environments, mainly in research labs. In the W3C Semantic Web Activity Statement we are told that: “The Semantic Web is a vision: the idea of having data on the Web defined and linked in a way that it can be used by machines not just for display purposes, but for automation, integration and reuse of data across various applications.[W3C 2001] ” [emphasis mine] As envisioned by Tim Berners-Lee: “The Semantic Web is an extension of the current Web in which information is given well-defined meaning, better enabling computers and people to work in cooperation.” [Berners-Lee et al 2001] [emphasis mine] “[S]omething has semantics when it can be ‘processed and understood by a computer,’ such as how a bill can be processed by a package such as Quicken.” [Trippe 2001] There is no widespread agreement on exactly what the Semantic Web is, nor exactly what it is for. From the above descriptions, there is clear emphasis on the information content of the Web being: • machine usable, and • associated with more meaning. Note that “machine” refers to computers (or computer programs) that perform tasks on the Web. These programs are commonly referred to as software agents, or sofbots and are found in Web applications. Machine usable content presumes that the machine knows what to do with information on the Web. One way for this to happen is for the machine to read and process a machine-sensible specification of the semantics of the information. This is a robust and very challenging approach, and largely beyond the current state of the art. A much simpler alternative is for the human Web application developers to hardwire the knowledge into the software so that when the machine runs the software, it does the correct thing with the information. In this second situation, machines already use information on the Web. There are electronic broker agents in routine use that make use of the meaning associated with Web content words such as “price,” “weight,” “destination,” and “airport,” to name a few. Armed with a built-in “understanding” of these terms, these so-called shopping agents automatically peruse the Web to find sites with the lowest price for a book or the lowest air fare between two given cities. So, we still lack an adequate characterization of what distinguishes the future Semantic Web from what exists today. Because RDF (Resource Description Framework) [W3C 1999] is hailed by the W3C as a Semantic Web language, some people seem to have the view that if an application uses RDF, then it is a Semantic Web application. This is reminiscent of the “If it is programmed in Lisp or Prolog, then it must be AI” sentiment