Semantic search

Semantic Search attempts to augment and improve traditional Research Searches by leveraging XML and RDF data from semantic networks to disambiguate semantic search queries and web text in order to increase relevancy of results.Hildebrand et al [ [http://swuiwiki.webscience.org/index.php/Semantic_Search_Survey Semantic Search Survey] ] provide an overview that lists semantic search systems and identifies other uses of semantics in the search process.

Guha et al [ [http://www2003.org/cdrom/papers/refereed/p779/ess.html www2003.org/cdrom/papers/refereed/p779/ess.html] ] distinguish two major forms of search: Navigational and Research. In navigational search, the user is using the search engine as a navigation tool to navigate to a particular intended document. Semantic Search is not applicable to navigational searches. In Research Search, the user provides the search engine with a phrase which is intended to denote an object about which the user is trying to gather/research information. There is no particular document which the user knows about that s/he is trying to get to. Rather, the user is trying to locate a number of documents which together will give him/her the information s/he is trying to find. Semantic Search lends itself well here.

Rather than use ranking algorithms such as Google's PageRank to predict relevancy, Semantic Search uses semantics, or the science of meaning in language to produce highly relevant search results. In most cases, the goal is to deliver the information queried by a user rather than have a user sort through a list of loosely related keyword results.

Other authors primarily regard semantic search as a set of techniques for retrieving knowledge from richly structured data sources like ontologies as found on the Semantic Web [http://www.aifb.uni-karlsruhe.de/WBS/pha/publications/ontology-ir-ictir07.pdf] . Such technologies enable the formal articulation of domain knowledge at a high level of expressiveness and could enable the user to specify his intent in more detail at query time.

Disambiguation

In order to understand what a user is searching for, word sense disambiguation must occur. When a term is ambiguous, meaning it can have several meanings (for example, if one considers the lemma "bark", which can be understood as "the sound of a dog," "the skin of a tree," or "a three-masted sailing ship"), the disambiguation process is started, thanks to which the most probable meaning is chosen from all those possible.

Such processes make use of other information present in a semantic analysis system and takes into account the meanings of other words present in the sentence and in the rest of the text. The determination of every meaning, in substance, influences the disambiguation of the others, until a situation of maximum plausibility and coherence is reached for the sentence. All the fundamental information for the disambiguation process, that is all the knowledge used by the system, is represented in the form of a semantic network, organized on a conceptual basis. [ [http://www.expertsystem.net/page.asp?id=1517&idd=143 Expert Systems] ]

In a structure of this type, every lexical concept coincides therefore with a semantic network node and is linked to others by specific semantic relationships in a hierarchical and hereditary structure. In this way, each concept is enriched with the characteristics and meaning of the nearby nodes.

Every node of the network (called Synset) groups a set of synonyms which represent the same lexical concept (called Synsets) and can contain:

* single lemmas ('seat', 'vacation'; 'work', 'quick'; 'quickly', 'more', etc.)
* compounds ('non-stop', 'abat-jour', 'policeman')
* collocations ('credit card', 'university degree', 'treasury stock', 'go forward', etc.).

The semantic relationships (links), which identify the semantic relationships between the synsets, are the order principals for the organization of the semantic network concepts.Startup companies involved in this sector include Powerset, Yedda, [http://www.trovix.com Trovix] and Hakia. [ [http://www.paidcontent.org/entry/419-hakia-raises-2-million-for-semantic-search/ Hakia raised $2 million for Semantic Search] ]

Applications

Semantic Web search engines index RDF data stored on the Web and provide an interface to search through the crawled data.

Examples of semantic web search engines include:
* [http://www.cklingo.com/ CK Lingo] Novorum Consulting Inc.
* [http://swse.deri.org/ Semantic Web Search Engine (SWSE)] Developed by DERI Ireland.
* [http://www.sindice.com/ Sindice] Developed by DERI Ireland.
* [http://watson.kmi.open.ac.uk/WatsonWUI/ Watson] Developed by KMi, UK.
* [http://www.yr-bcn.es/demos/microsearch/ Yahoo! Microsearch]
* [http://iws.seu.edu.cn/services/falcons/ Falcons] Developed by IWS China.
* [http://www.semanticwebsearch.com/query/ Semantic Web Search] Developed by Intellidimension Inc.
* [http://zitgist.com/ Zitgist Search]
* [http://www.kartoo.com/ Kartoo]
* [http://swoogle.umbc.edu/ Swoogle] Developed by the Ebiquity Group of UMBC, USA.
* [http://www.alphaworks.ibm.com/tech/emailsearch Semantic Email Search] Developed by IBM Research
* [http://www.biovista.com/bea Biolab Experiment Assistant] Developed by Biovista, Inc.
* [http://www.k-now.co.uk/ K-Search] Developed by [http://www.knowledge-now.co.uk/ Knowledge Now Ltd]

Examples of health domain specific semantic search engines:
* [http://www.curbside.md/ Curbside.MD] Developed by Praxeon
* [http://www.curehunter.com/research/keywordSummaryD003110-Colon-Cancer.do?selectedTab=networkGraph Semantic Health Search] Developed by CureHunter Inc., entity extraction and relationship network
* [http://www.searchmedica.com Search Medica] and [http://www.searchmedica.co.uk Search Medica UK] use knowledge of medical concepts to disambiguate, utilize synonyms and drill down on more specific concepts.

Examples of industry specific semantic search engines:
* [http://www.searchmining.net/ searchmining.net] Developed by Aspermont for the global mining industry
* [http://www.searchpetroleum.net/ searchpetroleum] Developed by Aspermont for the global petroleum and oil & gas industry
* [http://www.searchsupplychainlogistics.net/ searchsupplychainlogistics.net] Developed by Aspermont for the supply chain & logistics industry
* [http://www.searchconstruction.net/ searchconstruction.net] Developed by Aspermont for the construction industry

See also

*Semantic web
*Resource Description Framework

References

Several scientific event cover the topic of semantic search explicitly, such as the [http://km.aifb.uni-karlsruhe.de/ws/semsearch08 Semantic Search 2008 Workshop at ESWC'08] and the [http://www.yr-bcn.es/esair08 Workshop on Exploiting Semantic Annotations in Information Retrieval at ECIR'08] .