# Effort Estimation Approach through Extracting Use Cases via Informal Requirement Specifications
## 2 Materials and Methods
### Methods for Adapting Requirement Engineering with Textual Approach  
#### 2.2.1 Our Refined Fillmore's Case Mechanism  
Our proposed case mechanism has refined the semantic concepts of the original case grammar and has been applied to the requirement engineering [20; 21]. The case grammar modeling procedure can be used to extract use-cases from natural language-oriented informal requirements, which is a top-down method. In other words, it will identify from use-case identification in a larger unit to objects \begin{table}
\begin{tabular}{l l} \hline \hline
**Case** & **Definition** \\ \hline Agent & A person or entity causing a verb’s action to be performed. \\ Counter agent & The force or resistance against which a verb’s action is carried. \\ Object & An entity affected directly by a transitive verb’s action. \\ Experiencer & A person or thing affected by a verb’s action, replacing of the dative. \\ Source & The place from which something moves. \\ Goal & The place to which something moves. \\ Locative & Location or spatial orientation of the state or action. \\ Instrument & The inanimate entity causally involved in a verb’s action. \\ Time & The time of the event. \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Original Fillmore’s Case [15]. and functions in a smaller unit. Through refined methods, we expect to analyze the high level of requirements, which will develop high-quality software. Figure 1 shows the refined Fillmore's Case Mechanism on how to adapt UML with the case mechanism for use-case extraction. This method analyzes semantic relationships between words based on the main verbs. Therefore, processing natural language as requirement specifications may be more easily handled. Our refined case mechanism consists of eight cases: actor, secondary actor, object, source, theme, instrument and goal [15; 20]. We redefine the existing _agent_ case as an actor in the use-case diagram like changing agent to actor (A). The existing _dative_ case has a similar role as counter actor. We change dative to counter actor (CA). The existing object and experiencer cases are changed to object (O). Source and goal cases represent a location or a place of moving something. We integrate the two cases into _Source_ (S). _Instrumental_ and _locative_ cases are integrated into the instrument (I). In this study, we add 'theme object (TO)' of case Grammar in 1971. In addition, the goal (G) is added, which indicates system goal to achieve the needs of users of a system. This is different from the existing goal (\"The destination of a location or a place where something moves\"). Table 2 lists the categories of refined cases. They consist of a role, notation and meaning of arguments which are associated with each verb. These cases can analyze all requirement sentences by arguments with the categories of cases. _For example, the following example illustrates the defined case mechanism on the sentence as the semantic role that different objects play when a **ACTION** is carried out. An employee acts as the **ACTOR** initiating the purchase utilizing the INSTRUMENT of PURCHASE order. Each purchase order identifies a set \begin{table}
\begin{tabular}{l c c} \hline \hline
**Case** & **Notation** & **Definition** \\ \hline Actor & A & The instigator of the event/action. \\ Counter actor & CA & The force or resistance against which an action is carried out. \\ Object & O & The entity which moves or changes or whose existence is in consideration. \\ Theme & TO & The subjective entity of Objects \\ Result & R & “Entity” that comes into existence as a result of the action. \\ Source & S & Origin of object. \\ Instrument & I & Facility used in carrying out an event. \\ Experience & E & “Entity” that receives or accepts or experiences or undergoes the effect of an action. \\ Goal & G & Destination of object. \\ \hline Main Verb & V & A change defined by an event. \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Refined definition and notation of the Fillmore’s cases [20; 21]. Figure 1: Refined Fillmore’s case mechanism.