# Ontology-Based Representation and Reasoning in Building Construction Cost Estimation in China
## 2 Research Background
### Ontology Modeling and Representation  
[PERSON] et al. [20] presented an extension to the World Wide Web (WWW) named the Semantic Web, which is able to handle Web data without human intervention. Compared with the existing network, the Semantic Web can make data retrieval more accurate and improve knowledge sharing and reuse. Ontology is a key technology of the Semantic Web, originates from the philosophy domain, and has been widely adopted in research efforts in the artificial intelligence and computer science domain over the past two decades [21; 22]. The widely accepted ontology definition is \"an explicit and formal specification of a conceptualization,\" as given by [PERSON] [21].  
Several studies have been conducted related to the application of ontology to the AEC/FM industry. [PERSON] et al. [23] demonstrated the usability of IFC [3] for constructing a metadata model for RFI (Request for Information) that improved the retrieval of RFI-related information. [PERSON] and [PERSON] [24] developed a domain ontology for construction concepts in urban infrastructure products, and their ontology provided a conceptualization for knowledge in civil infrastructure. [PERSON] et al. [25] presented an ontology-based risk-management framework of construction projects throughout the project lifecycle. [PERSON] et al. [26] proposed a method to extract concepts, instances, and relationships from the engineering domain handbook and quickly built a base domain ontology. [PERSON] and [PERSON] [27] built a domain ontology for JHA (Job Hazard Analysis) that used the existing JHA documents from a construction company and checked the applicability of the safe approaches under specific conditions. In the infrastructure product ontology (IPD-Onto), entities are used to represent the core concepts within the domain of the utility infrastructure, and the five main entities used are Project, Process, Actor, Resource, and Product [24]. [PERSON] and [PERSON] [28] presented a framework aiming to improve access to a company's JHA knowledge by using ontologies for structuring knowledge regarding activities, job steps, and hazards. In the construction safety management domain, [PERSON] et al. [29] put forward an ontology consisting of three main domain ontology models: the Construction Product Model, Construction Process Model, and Construction Safety Model. [PERSON] et al. [30; 31; 32] proposed an ontology-based labor cost estimation model and New Rules of Measurement (NRM)-based ontology modeling by using ontology engineering methodology [33].  
In summary, there have been many studies regarding ontology modeling and representation. Some studies have proposed ontologies for product modeling, and others have proposed ontologies for key concepts in the construction domain. However, there have been very limited studies regarding automating reasoning in construction cost estimation by means of specific conditions, related concepts, and the smallest unit of work. This paper proposes a construction cost estimation ontology model by combining concept models, construction conditions, and work items.