# Ontological Representation of Smart City Data: From Devices to Cities
## 1 Introduction  
The term smart city refers to a city that manages, in an intelligent way, all its associated resources with the aim to enhance the quality of the services provided to citizens and to improve their quality of life [1, 2]. The smart city domain has been a topic of interest in many sectors around the world. Standardization bodies, for example, the International Telecommunications Union ([[https://www.itu.int](https://www.itu.int)]([https://www.itu.int](https://www.itu.int))) and the International Standards Organization ([[https://www.iso.org](https://www.iso.org)]([https://www.iso.org](https://www.iso.org))), have been working on defining standards and recommendations in order to provide a unified way to refer to and manage this particular field. In addition, several initiatives and projects in the smart city field have emerged, which denote the efforts and investments that industries, countries, and regions are making in order to manage the city resources in a better manner. In the case of city coalitions or research groups (e.g., Smart Cities-European Medium-Sized Cities ([[http://smart-cities.eu](http://smart-cities.eu)]([http://smart-cities.eu](http://smart-cities.eu))), Open and Agile Smart Cities ([[http://www.oascities.org](http://www.oascities.org)]([http://www.oascities.org](http://www.oascities.org))), Smart Cities Council ([[http://smartcitiescuncil.com](http://smartcitiescuncil.com)]([http://smartcitiescuncil.com](http://smartcitiescuncil.com))), etc. ), their studies and business reports mention more than 300 smart cities involved [3] with an increasing need for and interest in exploring solutions in order to improve their city processes. In the case of projects (e.g., ESPRESSO [4], CityPulse [5], SmartSantander [6], etc. ), which are financed by public, private, or a mix of both funds, they aim, in most cases, to provide technological tools to solve requirements in several city challenges. In this respect, there is wide agreement about the fact that smart cities are characterized by a pervasive use of information and communication technologies [7, 8, 9], which, in various urban domains, may help cities make better use of their resources [10]. Some of these technologies include open data infrastructures, mobile applications, public participation tools, Internet of Things (IoT) platforms, etc. The data handled or produced by all these technologies is very heterogeneous in terms of formats, structure, and delivery mechanisms, both inside the same city and across different cities. Hence, this opens up the opportunity to create common models to allow interoperability inside cities. In this context, ontologies, understood as formal specifications of shared conceptualizations [11], can be usedto provide such models in a reusable and extensible manner. Several smart city ontologies have been developed in order to represent data related to cities (e.g., [12; 13; 14; 15; 16]). However, these ontologies rely on very specific ontological commitments for their particular needs, which makes data interoperability harder to achieve. In order to minimize these strong commitments and to avoid developing large monolithic ontologies, small and generic ontology snippets, which capture key and reusable knowledge, may be used [17]. In ontological engineering these snippets have been used since the early 2000s and are known as Ontology Design Patterns (ODP). ODPs are inspired by software design patterns and can be understood as a reusable modeling solution to a recurrent ontology design problem [18]. Regarding the above-mentioned design strategy, a related approach for smart city knowledge management has been addressed in [19]. In this work, nine patterns have been identified based on the analysis of the Toronto 311 web pages. However, these patterns are only focused on representing municipal knowledge from citizen requests, and some of them rely on specializations that could be generalized (e.g., education, citizen, species, etc.).