Which Semantic Web? Marshall & Shipman* Problems with formality Conclusion: Semantic web design and adoption questions Three semantic web perspectives Pragmatic issues: The world-wide web does NOT have a consistent structure; it is not ordered or classified. Cognitive overhead: learning the representation (syntax and semantics) and making decisions on how to represent knowledge. Tacit and evolving knowledge Premature structure: - impedes & impairs classification - incremental structure development req'd. Situated nature of knowledge Sub-divide ideas & entities Find appropriate concepts Create concepts (when needed): - name it - connect to other concepts by attaching attributes and relations Knowing what to express (a learn by doing, trial and error, process) What is tacit knowledge? (Unspoken knowledge that may not be expressible in explicit language.) Formal representations are rigid (poor match for natural communications) Understanding of what is knowledge changes over time Natural categorizations (people give different names and attributes to the same objects in different contexts) Knowledge representation is problem dependent (attributes for objects and contexts are not enumerable (Kent, 2003 ?)) Knowledge stability (How well are the domain and its practices understood? How much formalization and restructuring is expected, or can be tolerated?) Competing conceptual approaches (Is the knowledge intrinsic or extrinsic? Can intrinsic structure be recognized with heuristic approaches; can declared representations be avoided or minimized?) Negotiation among information resource stakeholders (What roles do negotiation, facilitation, or intervention play in representing knowledge in a socio- technical framework? Are there identified and accepted approaches that work in the domain?) Universal Library: Existing tools (e.g., search) are sufficient; extend the web by defining and linking web information; enable more effective discovery, automation, integration, and reuse. Computer agent environment: Software agents can use defined and linked information to find, filter, and prepare information for people and procedures. Implementation is too hard in theory and in practice: (i) context-free knowledge representation relies on domain orientation; (ii) there is always a situation where more contextual information is needed. Federation of knowledge/data bases: most promising, can leverage information in existing relational databases, but requires - knowledge engineering (including social processes) - cataloging - librarianship Unruly properties of the (semantic) web: (i) AAA slogan (anyone can say anything about any topic; (ii) open world/ closed world (anyone can say something new about anything, hence there could always be more information); (iii) non- unique naming (many names for the same thing); (iv) it is an information wilderness (no guarantees that information is orderly or understandable) (Allemang & Hendler, 2011). Semantic Web as a metadata system Semantic Web as markup: HTML example; how complex and complicated will semweb markup get? (See W3C work on RDFa and Schema.org for current approaches. (LiDRC, 2010), (W3C, 2012).) Semantic Web as killer app: primary challenge is that it is difficult to keep detailed preferences in line with moment-to-moment needs Community centered: every aspect of metadata (collecting, validating, using) is a local practice; no set of cataloging rules ever fully prescriptive (cf. W. Kent, 2003). Cost: every metadata standard has an associated cost; each implementation must decide how much and who bears it? Authority and trust: knowing that the metadata is a good representation of content for its intended use is a challenge; needed early, but not later? * Marshall, C. & Shipman, F., Which semantic web?, Hypertext'03 (2003). Retrieved 2013-02-17 from: http://dx.doi.org/10.1145/900051.900063. W.L. Anderson, 2012, 2013, CC-BY References. Allemang, D. & Hendler J. (2011) Semantic Web for the Working Ontol