# Natural Language Processing in Knowledge-Based Support for Operator Assistance
## 3 Methodology
### The Dataset  
In our approach to building a benchmark dataset for the assembly domain, we categorize sentences based on two distinct structures commonly found in assembly-related content: imperative and declarative sentences. In NLP, imperative and declarative sentences are two types of sentence structures with distinct characteristics and functions [86]. An imperative sentence is a type of sentence that gives a command, makes a request, or gives an instruction. It is usually written in the present tense and begins with a verb. On the other hand, a declarative sentence is a type of sentence that makes a statement, expresses a fact, or conveys information. It typically has a subject and a predicate. In a benchmark, a representative portion of the multiple-class category refers to a balanced distribution of the data across all the classes in the classification task. [PERSON] [70] with 350 questions in their benchmark, considering different classes on sentence structures, categorized 80% of the questions as interrogative, 11% as imperative, 5% as declarative, with 4% categorized as others [87]. In the TV show database benchmark with 25,076 statements, considering two categories as imperative and non-imperative, imperative statements took up about 8.8%. In assembly benchmarks, both imperative (directive) and declarative (descriptive) sentences can be used. Imperative sentences are often used for instructions and informative sentences, such as \"Place the part in the machine and press start\", while declarative sentences are used to convey information or describe a process, such as \"The machine automatically aligns the part before beginning the milling process\". Both types of sentences can be used in different tasks of the benchmark, such as text classification, information extraction, and question answering. \begin{table}
\begin{tabular}{l l} \hline \hline
**Class of Tags** & **Description** \\ \hline _Noun_ & Refer to entities in the world like people, animals, and things \\ _Verb_ & Describe actions, activities, and states \\ _Adjective_ & Describe properties of nouns \\ _Pronoun_ & Used as a substitute for a noun or noun phrase \\ _Determiner_ & Providing additional information or to specify the reference of the noun \\ _Adverb_ & Modify verbs, adjectives, providing extra information \\ _Preposition_ & Prototypically express spatial relationships \\ _Conjunction_ & Used to connect words, phrases, or clauses within a sentence \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Considered classes of part of speech tags. Figure 2: Visualizing part-of-speech tags for two sentences. However, considering the mentioned categories in the different academic references and also taking into account the different documents used in the assembly line in the assembly domain, in this research, we consider four different categories in the assembly domain as follows: Warnings, Informative texts, Manuals, and Work instructions. * Manual documents are important in manufacturing as they provide detailed instructions on how to operate, maintain, and repair various types of equipment. (The manual is on the level of equipment.) These documents typically contain textual descriptions and diagrams or illustrations to help users better understand the processes involved. Manuals may also include technical documents used in manufacturing, such as installation manuals, service manuals, and troubleshooting guides. The manual mostly includes declarative sentences. * Warning documents in manufacturing are documents that provide warnings and safety instructions to users who may operate or come into contact with machinery or equipment. These documents are typically included with products or machinery and provide information on how to properly operate, maintain, and service them to avoid potential hazards. Examples of warning documents in manufacturing include safety manuals, warning labels, caution tags, and safety data sheets.