State-of-the-Art: Semantics Acquisition and Crowdsourcing - Semantic Acquisition Games: Harnessing Manpower for Creating Semantics - page 8

Chapter 2
State-of-the-Art: Semantics Acquisition
and Crowdsourcing
Abstract In this chapter we review the field of semantics acquisition to provide
ground for further discussion on the semantics acquisition games. First, we cover
the necessary definitions and review the main “client” approaches for semantics
utilization—the information retrieval applications. Then, we move through three
major groups of semantics acquisition approaches. The first group constitutes the
expert-based approaches: costly, yet often essential for certain tasks such as seed-
ing, setting-up schemas and semantics acquisition output validation. As second,
we review the automated approaches: quantitatively effective, yet with questionable
quality of output, widely utilized for many tasks such as ontology learning or resource
metadata acquisition. Finally, we review the crowd-based approaches, which repre-
sent a balance between quality and quantity. They comprise many working schemes,
ranging from “explicit” mechanical turking, to “implicit” social tagging applications
and of course semantics acquisition games.
2.1 Semantics: Forms and Standards
In general, the term semantics stands for “meaning” and has many interpretations
depending on the domain it is used in (e.g., philosophy, linguistics, programming).
In the web science field it stands for a formally and explicitly represented meaning of
resources (of theWeb) readable and “understandable” bymachines. At first look, such
definition covers only the direct descriptions of resources (such as tags describing an
image), however, in practical use, it covers also “not-so-direct”, formally expressed
facts, which are also part of meta-information layer above the Web, the domain
models (which define the axioms and facts about the world they model). In our
work, we use this broader definition. The web semantics is then the whole layer of
semantics above the web resources. The Semantic Web is its subset that uses specific
formalisms, which arewidely accepted in the community as semantics representation.
The semantics comes in different flavors according to their representations and also