# Resilient Scheduling as a Response to Uncertainty in Construction Projects
## 2 Resilience Approach to Manage Uncertainty in Construction Projects
### Taxonomy  
Herein, a voluminous body of information is deliberately omitted, aiming to present only the fundamental principles in the process of creating the taxonomy model. Taxonomy is modeled by the use of the open-source platform Protege. The taxonomy model serves as a basis for modeling the impact of uncertainty on baseline schedules in the final step of resilient schedule validation. In this study, the taxonomy model is a representation of domain knowledge by the use of concepts organized into facets and/or hierarchical structures. In the multifaceted taxonomy, every facet represents different features of the concept which is classified [57]. For example, one facet embodies uncertainties considering project life-cycle phases, and the other depicts uncertainties regarding stakeholders in a construction project, etc. Each of the facets could be further described by an independent taxonomy [57], either in hierarchical, faceted, or combined form. The taxonomy model is developed to account for a high variety of possible events and conditions that could occur and affect project objectives. As the main objective is the development of construction schedules that are resilient to disruptions stemming from uncertainties, the starting point, i.e., universe of discourse of the taxonomy, is determined as \"Uncertainty sources in a construction project\". The main concept is further depicted by sub-concepts, i.e., facets, which ought to exhaustively describe the universe of discourse. Faceted systems are in their nature general knowledge management models based on a multidimensional classification of heterogeneous data [57]. Since different authors argued sources of uncertainty in construction projects in a constrained way, e.g., solely with impact on transaction cost [56], multifaceted classification was imposed on the representation of the gathered knowledge. The main concept is depicted by sub-concepts, i.e., facets, which ought to exhaustively describe the universe of discourse. To maintain integrity while modeling sub-dimensions (facets) of the main concept, fundamental categories were developed by following the core principles of knowledge organization, referring to five fundamental categories of knowledge classification [58], as presented in Table 1.  
The facets are revealed through the literature review, and they tend to describe the main concept exhaustively. To prevent ambiguity or vagueness of any kind, we offer five main facets:  
* Member facet tends to describe all aspects of human attributes together with their mutual relationships which could lead to project perturbations. Members in a construction project could be individuals as well as groups of people, i.e., organizations. * The project is described as features of a construction project which represent substantial means of how a project affects uncertainty existence. * Impact means all the direct effects of uncertainty sources on traditionally determined project objectives (schedule-budget-quality goals), with additional sustainability aspects [59]. * Causes are states, conditions, and events in which sources of uncertainty are triggered. * The life cycle presents stages of a construction project in which uncertainties may arise. This facet is the time dimension of the universe of discourse. The structure of five main facets further depicted with the second-level entities (subfacets) is shown in Table 2. Currently, the taxonomy model counts more than 300 entities in the form of mutually categorized terms, accompanied by the definition for each term to prevent any ambiguity. While the main idea of classification is to systematically represent the integrity of the source term, compounding terms is the process of composing different concepts to form a distinct term. For example, the term \"Crane failure due to mechanical malfunctions or breakdowns\" is compounded from concepts \"Resources\" and \"Breakdowns\", so there is no need to explicitly denote the existence of the compound term.