## 2 Related Work  
In most construction projects, structural, mechanical, electrical, and plumbing (MEP) engineers develop their designs based on the architectural model. This base model is often constantly updated along with the progress of the design work. Without the adequate synchronization of all the updates among these design teams, there will be so-called \"design clashes\". It refers to a conflict of building components overlapping each other spatially when various types of engineering drawings are compiled. As pointed out by some scholars, if a collaboration environment exists between design teams, most clashes can be avoided [7]. However, in the participatory action research of the United Kingdom, researchers introduced a collaboration environment in a multi-floor large-scale construction project, where the engineers were assisted by software to avoid design clashes. However, there were still more than 400 clashes found between the structural model and the MEP model [4]. Their study pointed out that collaboration can indeed reduce design conflicts, but clash detection is still a necessary operation. In the era of 2D drawings, design conflicts were not easily detected at the design phase, but remained until the construction, leading to reworks or even change orders. Clashes have been regarded as one of the major factors causing cost overruns and project delays. The emergence of BIM software enables easy design conflict/clash detection; conflict checking has been one of the essential functions of BIM software. However, [PERSON] et al. [5] found that those clash detection algorithms in most BIM software are relatively simple: as long as two building components are spatially overlapping, touching, or within a given distance, they are recognized as conflicts and are listed in the detection report. Identifying and resolving those detected clashes is a time-consuming and laborious task [4; 6; 7]. The clashes detected by BIM software can be roughly divided into three categories: (1) errors, which are the clashes that will affect the project and must be resolved, such as structural components penetrated by pipes; (2) deliberate clashes, which includes intentional clashes originating from the designer, such as the pipes and conduits penetrating through the slabs; (3) pseudo clashes, which are permissible clashes appearing to be errors. As [PERSON] and [PERSON] [17] discovered, the proportions of deliberate and pseudo clashes, which are also known as \"irrelevant clashes\", in a particular project were up to 50% [10]. Among the cases considered in our study, this proportion was even higher. Scholars termed these conflicts that do not have substantial impacts on the project as \"irrelevant clashes\" [6; 7]. These irrelevant clashes can be discovered in subsequent project stages and easily handled by the site engineers themselves; therefore, there is no need to resolve them during the clash detection. However, the clash detection report of BIM software does not disclose these irrelevant clashes, which means they must be manually identified by BIM managers instead. As pointed out by [PERSON] et al. [7], in practice, many projects can have millions of clashes, so automating the filtering of irrelevant clashes is an important and urgently needed function [4; 6; 7]. Existing methods of reducing irrelevant clashes can be roughly divided into three aspects: clash avoidance, clash detection improvement, and clash filtering [7]. Clash avoidance begins with the modeling method during the design phase, emphasizing the collaboration and coordination among the design teams to avoid the occurrence of clashes from the beginning. [PERSON] et al. [18] established taxonomy to classify the causes of clashes into three categories, namely, process-based, model-based, and physical design [12]. They aimed to understand the causes of design conflicts and the consideration factors for conflict/clash resolution.