Handling temporal granularity in situation-based services

In many application fields such as disaster management or personal planning, efficient mobile services should capture users' context in order to provide them with the most appropriate information at a given time. Situation-based services aim toward this direction. They go beyond location-based services as they take a user's current situation into account. Situations include user profiles together with dimensions such as their location, current activity, or type of connectivity. They can be derived from direct observations or from electronic calendars and are defined as valid during a time interval. Depending on the application but also within the same application the time interval of interest can be of various granularities. It is crucial to handle time granularity efficiently and in a welldefined manner. In this paper, we investigate the handling of various granularities for situations and situation sequences through, in particular, coarsening methods. We propose an algorithm that we tested in concrete projects and we illustrate its use in a tourism application.