ontologies
1.1 Basic Concepts When we think of a process in any given domain, we generally figure it out as a series of actions that leads to a certain outcome. For a construction project, when it comes the execution phase, the process of site planning and activity scheduling can be assumed as what the planner does in the search for the solution of a complex and faceted problem whose variables are numerous (building design, site characteristics, boundary conditions, technology, materials, labor, etc.) and most of the times, if not unknow, at least highly uncertain. As a matter of facts, the planner deals with this problem (process) on the base of his experience or, in other words, of the knowledge he owns about the problem. As simplistic as this statement could seem, gives us the reason to look more closely to what “knowledge” means and which role does it play for our purpose. Knowledge is understanding of a subject area (Durkin 1994). It comprises concepts and facts about that subject area, including relations among them and mechanisms for how to combine them to solve problems in that area. Now, this roughly corresponds to what we want to achieve by mean of a computer-aided system capable of simulating what an expert would do for a given problem, acting in a way that humans usually call “intelligent”. This is why “artificial intelligence” (AI) is used to indicate the branch of computer science that attempts to approximate the results of human reasoning by organizing and manipulating factual and heuristic knowledge. (Bandwidth Market 2008). In AI, knowledge is pivotal: it is stored, encoded in a suitable format, into computer memory in order to be retrieved when it is needed for reasoning or, otherwise, to obtain conclusions, inferences and explanations applying problem-solving strategies. Taking a step back, none of these actions could be done before knowledge acquisition which consist, namely in gathering, organizing, and structuring knowledge about a topic, a domain, or a problem area, in order to prepare it for putting into the system. This is where humans decide on how to represent knowledge inside computers. For this purpose, in AI, a number of different representations, or models, have been developed to be
