Elsevier

Journal of Web Semantics

Volume 6, Issue 1, February 2008, Pages 14-20
Journal of Web Semantics

Metcalfe's law, Web 2.0, and the Semantic Web

https://doi.org/10.1016/j.websem.2007.11.008Get rights and content

Abstract

The power of the Web is enhanced through the network effect produced as resources link to each other with the value determined by Metcalfe's law. In Web 2.0 applications, much of that effect is delivered through social linkages realized via social networks online. Unfortunately, the associated semantics for Web 2.0 applications, delivered through tagging, is generally minimally hierarchical and sparsely linked. The Semantic Web suffers from the opposite problem. Semantic information, delivered through ontologies of varying amounts of expressivity, is linked to other terms (within or between resources) creating a link space in the semantic realm. However, the use of the Semantic Web has yet to fully realize the social schemes that provide the network of users. In this article, we discuss putting these together, with linked semantics coupled to linked social networks, to deliver a much greater effect.

Introduction

In talking about the Web, whether the original model, the so-called “Web 2.0”, or the emerging Semantic Web (aka Web 3.0), one of the most important things to keep in mind is the network effect. The power of the Web emerges through the link space realized between Web pages. This is evidenced in a number of pieces of work, most famously the PageRank algorithm [1] that was behind the early success of Google. Unlike traditional information retrieval algorithms, which were solely based on the information content of the individual pages, PageRank takes into effect how Web pages are linked to each other. By coupling this information with traditional indexing schemes, the system was able to outperform its competitors.

The network effect describes the value of a service to a user that arises from the number of people using the service. At its core, it captures that value increases as the number of users increases, because the potential links increase for every user as a new person joins. This is best quantified by what has come to be known as Metcalfe's law. This proposition developed by Bob Metcalfe in the early 1980s, was originally defined to better explain to his customers why they needed more Ethernet boards than they were buying.1 Metcalfe hypothesized that while the cost of the network grew linearly with the number of connections, the value was proportional to the square of the number of users. For example, given n users of ethernet cards, the number of possible connections that can be made is n(n  1) = O(n2).

Metcalfe's law has been used to explain the growth of many technologies ranging from phones, cell phones, and faxes to web applications and social networks, especially online social networks. The intuition clearly holds that as the number of people in the network grows, the connectivity increases, and if people can link to each other's content, the value grows at an enormous rate.

Recently, there has been some interesting debate with respect to the validity of Metcalfe's law. On the low end, in a 2006 column in IEEE Spectrum, Briscoe et al. [2] opined that value in a network grows more like O(n log n) arguing that not all connections are of equal value. At the other extreme, in a 2001 article in Harvard Business Review, Reed [3] claimed that the value of the network grew exponentially in the number of connections. His argument is essentially that in a largely connected network, such as a social networking Web site, the value is in the creation of subgroups and the number of these subgroups (i.e. the subnetworks of size 2, size 3, …, size n) grows exponentially with n. While none of these effects have been validated in practice, it is clear that the network effect is quite real, and even the most pessimistic view still provides for significant value as the number of connections in the network grows.

There is a corollary of Metcalfe's law that is sometimes missed: for the network effect to happen, linking must be present. The Web, if it were simply a collection of pages of content, would not have the value it has today. It is precisely because every Web page can, in principle, link to any other page that the Web has grown as it has. Without this linking, information would get cut and pasted onto larger and larger individual pages; instead of the Web, we would have a large number of disconnected pages and little or no index.

In this paper, we look at Web 2.0 and Semantic Web applications from the point of view of the linked spaces being created – where does the network effect come from? The social nature of Web 2.0 sites primarily allows linking between people, not content, thus creating large, and valuable, social networks, but with impoverished semantic value among the tagged content. Conversely, the Semantic Web is able to take advantage of significant linking in semantic space, and while it can represent social networks, it does not have social constructs that lead to linking between users. Furthermore, many production level Semantic Web applications are not exploring how to create links between different ontologies. We will look at how a combination of these could be designed to take advantage of the joint network effects of links in social space with links in the semantic space. By combining the social networks of Web 2.0 with the (small “s”) semantic networks of the Semantic Web, a tremendous value is promised.

Section snippets

Web 2.0 as a social phenomenon

Much is made of the incredible success of so-called “Web 2.0” applications, even though there is no widely agreed upon definition of what makes something one. In a widely cited web article, O’Reilly, who is generally considered to have coined the term, discusses the many aspects of Web 2.0 [4]. The discussion includes exploring the technologies of AJAX, Web Services and other means for making Web content more dynamic. In this view, Google Maps is considered the prototypical Web 2.0 application,

The Semantic Web graph

Some of the original motivations for the Semantic Web came from the very same failures in early Web applications that cause the problems for search and browsing in Web 2.0 applications. Latent Semantics, the attempt to “mine” meaning from the words in Web content, is always problematic due to ambiguity and polysemy (the many meanings of a single word such as “run” or “left”). Also problematic are the class and subclass relations that are crucial to language use. For example, a search for

Putting it together

A recent boom in Semantic Web technologies has been occurring in the so-called “Web 3.0” technologies. In these systems, an attempt is being made to exploit more of the link spaces inherent in RDF-based systems coupled with capturing some of the social dynamics of Web 2.0 applications. One difference between these and earlier AI systems is the attempt to figure out how to exploit the increased value of the network effect that can come from using Semantic Web technologies to provide links

A research vision

The Web is an interesting place for browsing, but its real power derives from people finding what they need. Similarly, using Semantic Web technologies, social networks, and terminologies to label and link content will be powerful only when it enables people to do powerful things. Creating these links is a first necessary step, and the research challenges lie in understanding how to use them.

Building expressive Semantic Web ontologies is very difficult to do well, but once they are built a lot

Conclusion

Although there is great mythos about Web 2.0 and the Semantic Web, there is no real reason to believe they function significantly differently with respect to linking than other existing information systems, particularly the original “Web 1.0.” Metcalfe's law makes it clear that the value of these systems, viewed as networks of communicating agents (whether human or machine), arises from the many connections available between online resources. To exploit this space, however, there must be

References (17)

  • J. Golbeck et al.

    The national cancer institute's thesaurus and ontology

    J. Web Semant.

    (2003)
  • S. Brin et al.

    The anatomy of a large-scale hypertextual web search engine

  • B. Briscoe et al.

    Metcalfe's Law is wrong

  • D.P. Reed

    The law of the Pack

    Harvard Business Rev.

    (2001)
  • T. O’Reilly, 2005, What is Web 2.0? Design Patterns and Business Models for the Next Generation of Software, September...
  • C. Shirky, 2003, The Semantic Web, Syllogism, and Worldview,...
  • A. Marcus et al.

    m-YouTube mobile UI: video selection based on social influence

  • C. Marlow et al.

    HT06, tagging paper, taxonomy, Flickr, academic article, to read

There are more references available in the full text version of this article.

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