# An Operations Chain Model for Automatic Assessment of Operation Procedure for Equipment Operators
## 2 Operations Chain Model
### Basic Concept  
To completely describe the operations chain model, the following terms are defined:  
1. Basic operation. Basic operation refers to the indecomposable operations that must be carried out as a whole according to specific equipment and system requirements. For example, the procedure of manually starting a pump can be divided into three basic operations: turning on the power, switching to manual control, and pressing the start button. Basic operations can be represented by digits or letters.
2. Operation function module. Operation function module refers to the combination of basic operations or other operation function modules. For simplicity, it is also called a function or function module.
3. Operation tree. Operation tree is a tree structure composed of basic operations and their combinations according to certain relationships. An operation tree will represent a specific functional module, such as pump startup.
4. Operation node. The operation node refers to a node within a sequential operations chain, which represents an operation tree for carrying out a specific function.
5. Operations chain. The operations chain comprises a series of operation nodes arranged in a specific chronological order, providing a comprehensive description of the operation procedure specified in the operation manual.  
The operation tree is comprised of basic operations organized according to the logical relationships, as shown in Figure 1. The operation shown in the figure refers to the basic operation. The vertices of the operation tree correspond to the operation nodes. The whole tree is formed by basic operations and their function combination using logical relationships of \"AND\" (&), \"OR\" (+), and \"MEX\" (\(\times\)). Each function can be composed of basic operations, or function combinations of any of the three relationships mentioned above. It forms a tree-like structure that combines all operations of a chain node by function analysis. To obtain the functionality of an operation node, multiple paths may be derived from the tree. Additionally, the operation tree model facilitates search implementation and can incorporate more information relevant to the assessment. It is important to note that there are only logical relationships between basic operations and operations combinations in the operation tree, with no sequential relationships. Sequential relationships are only reflected in the operations chain.  
The operation nodes are strung together in a certain order to form the operations chain, as shown in Figure 2. Each node in the operation chain is an operation tree. The order of the operation nodes cannot be changed in the operation chain.  
Figure 1: Schematic of the operation tree (operation nodes).  
Figure 2: Operations chain model.  
The operation tree (operation node) is used to describe the logical relationships among operations and functional groups such as \"AND\", \"OR\", and \"MEX\". The operations chain describes the sequential relationships among operation nodes. The whole operations chain model can describe the process, path, and sequence of the operations. Therefore, it can provide comprehensive standard information for assessing algorithms.