## 3 The Notion of Context  
Despite the large amount of research work in the field of Artificial Intelligence, there is no concise definition of a context [23]. This makes it difficult to select a logical structure of representation and reasoning when context-dependent information is involved, in particular the one generated by WSNs. In this paper, we have used the metaphor of a box as proposed by [PERSON] and [PERSON] [24]. In this case, a context is a box that can be divided into two parts (Figure 1): \begin{table}
\begin{tabular}{l l l} \hline \hline
**Data** & **Metadata Elements (MD)** & **Value (V)** \\ \hline T = 22 & Phenomena & Temperature \\  & Data unit & Celsius degree \\  & Time Result & 2009/01/23 19:23:45 \\  & Location & Lat 40\({}^{\circ}\)26 North; Long 3\({}^{\circ}\)42’West \\  & Feature of Interest & Technical University of Madrid Campus \\  & Mote type & mts420 crossbow \\  & Sensor Type & Sensirion SHT11 \\  & Other data associated & Humidity, Barometric Pressure, Ambient, \\  & & Light Sensors, Dual-Axis Accelerometer, \\  & & GPS position. \\  & Node identifier & 5 \\  & Number of nodes in network & 11 \\  & Number of node neighbours & 7 \\  &.... &.... \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Examples of WSN metadata elements for temperature data. * inside the box: a collection of WSN status that describes the status of a WSN over time,
* outside the box: a collection of metadata elements (MD) and their respective values (V). The assumption is that the content of what is inside the box is determined by the values of the metadata elements associated with that box. In other words, the contexts of a WSN's status are inferred using metadata elements that describe the sensing system, the current network configuration, and the environment restrictions. To address the box metaphor into the dynamic interoperability of WSNs, two considerations must be made [25]. First, the dynamic WSN status (and its required self-adaptation) is considered as a local model, in the sense that the WSN's status is based on local information. This has to do with the relationship between metadata elements and their values, and the representation of a context inside the box. For example: How the metadata elements and their values affect the representation of a WSN's status? In what sense a metadata element provides implicit information which can be used to infer a context for interpreting what is inside the box? Second, the dynamic interoperability is considered as a global model in the sense that happens across multiples and heterogeneous WSNs and with multiple and shareable context representations. The issue here has to do with the relationship among the boxes. For example: How do these relationships affect the contents of different boxes? Therefore, the connection between global and local models can only be achieved by the representation and reasoning on different contexts. Contextualising WSN interoperability can be achieved by using reasoning rules, between dynamic interoperability (global model) and the WSN's status (local model). The contexts are local (where local is intended here to imply not shared) models that encode a party's view of a domain [25]. In the scope of our research, the parties are the WSN that interoperate; the domain is the dynamic interoperability and the view of a domain is the current status that has influence over its dynamic interoperability. Thus, in our model _contexts are local models that represent the current WSN status in the domain of dynamic interoperability_ (Figure 2). [PERSON] [25] also points out that the notion of context is best used in those applications where the core problem is the use and management of local and autonomous representations. This is particular the case of WSN applications. Moreover, contexts are easier to define and maintain. They can be constructed with no consensus among different WSNs, or only with the limited consensus which make it possible to achieve the desired level of communication.