application • a knowledge base to support construction planning
widespread ontology language (Baader et al., 2003), the reasons of its choice are twofold, as reported below: e. BIM systems and models are equipped with a standardized interface for data exchange which is the IFC (Industry Foundation Classes) standard (OpenBIM, 2016)3. Some pilot schemes in academic research have tried to make IFC available as an OWL ontology to allow the usage of semantic web technologies as explained in Drogemulle and Schevers (2005) and Beetz (2009). Thanks to these research efforts, it is only a short while since the ifcOWL ontology, which is precisely meant to be used to allow extensions towards other structured data sets, is available. This would mean that a practical data-exchange between a given BIM and our model could be established. f. The possibility that the Knowledge Base relies on the ontology which underpins a BIM, would accomplish higher robustness in the future to any software applications whose functioning is based on the presented KB. In this way, it would also be possible to provide our modelling domain (classes, relationships and properties) with a logical and ontological link with BIM ontology (ifcOWL). Based on these assumptions, in the next paragraph we present and specify the ontological structure of the Knowledge Base. 3.1 Ontological structure of the Knowledge Base In this section the assumption on which the author built the Construction Process Ontology are described. The presented ontology consists in a formal description of concepts (OWL classes) referred to the task of construction planning and scheduling. Each concept, within the ontology, is described by using various relationships with other concepts or attributes (OWL properties) and restrictions on properties (OWL restrictions). The properties define precisely the requirements for membership of the class. Such an ontological framework together with a set of instances (OWL individuals) that specify the ontology application to a case study, forms a Knowledge-Base. More precisely ‘OWL properties’ are binary relations on classes (see ‘requires’ in Figure 3.2) of mainly two types: • Object-properties. They are relations between two classes or individuals. • Datatype-properties. They link an individual to a Datatype-value (e.g., real number, decimal number, string, Boolean value, time instance, etc.) In other words, they are used to relate an individual to a concrete data value. 3 BuildingSMART maintains a framework for software companies to collaborate in supporting open standards for BIM.
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