Citations are the ultimate "linked data" of academia, linking new work with related works. The problem is that the link is human-readable only and has to be interpreted by a person to understand what the link means. PLOS Labs have been working to make those citations machine-expressive, even though they don't natively provide the information needed for a full computational analysis.
Given what one does have in a normal machine-readable document with citations, they are able to pull out an impressive amount of information:
- What section the citation is found in. There is some difference in meaning whether a citation is found in the "Background" section of an article, or in the "Methodology" section. This gives only a hint to the meaning of the citation, but it's more than no information at all.
- How often a resource is cited in the article. This could give some weight to its importance to the topic of the article.
- What resources are cited together. Whenever a sentence ends with "", you at least know that those three resources equally support what is being affirmed. That creates a bond between those resources.
- ... and more
This is just a beginning, and their demo site, appropriately named "alpha," uses their rich citations on a segment of the PLOS papers. They also have an API that developers can experiment with.
I was fortunate to be able to spend a day recently at their Citation Hackathon where groups hacked on ongoing aspects of this work. Lots of ideas floated around, including adding abstracts to the citations so a reader could learn more about a resource before retrieving it. Abstracts also would add search terms for those resources not held in the PLOS database. I participated in a discussion about coordinating Wikidata citations and bibliographies with the PLOS data.
Being able to datamine the relationships inherent in the act of citation is a way to help make visible and actionable what has long been the rule in academic research, which is to clearly indicate upon whose shoulders you are standing. This research is very exciting, and although the PLOS resources will primarily be journal articles, there are also books in their collection of citations. The idea of connecting those to libraries, and eventually connecting books to each other through citations and bibliographies, opens up some interesting research possibilities.