RDFS also captured significant variability in fatigue throughout the day.
For our development of the RDFS, we used a numerical rating scale similar to a visual analog scale (VAS) developed by Krupp et al [12].
Because the RDFS is based on a 0- to 10-point numerical rating scale that queries each subject to longitudinally quantify their absolute level of fatigue, RDFS is constructed to have good face validity as a direct measure of fatigue severity.
Given an RDF graph T, the required space complexity to store the RDF document represented by T is 0([absolute value of T]).
In the labeled directed graph model, given an RDF graph T, the set of nodes W is comprised of elements in sub(T) [union] obj(T), and the set of arcs E is composed of elements in pred(T) [3,5].
First, a resource may simultaneously appear as a predicate, a subject and/or an object in the same RDF graph.
A triple <S, P, O> [member of] R x U x (R [union] L) is called an RDF triple where U is a set of URI references (URls), L is a set of literals, B is a set of blank nodes, and R is a set of U union B.
An RDF statement also can be modeled as a directed graph of node and arc representing the resource, and its property and value.
Another characteristic of RDF is that it is a property-centered model.
For instance, RDF gives us the ability to discover that there is an article about the Giant Squid at one of my web sites, and that the article was written on a certain date by a certain person, that it is associated with three other articles in a series, and that the general theme associated with the article is the Giant Squid's earliest roots in mythology.
All of this information is easily produced and consumed through the benefits of RDF without having to rely on any extraordinary computational power.
However, for all of its possibilities, it wasn't long after the release of the RDF specifications that concerns arose about ambiguity with certain constructs within the document.