# An Ontology-Based Expert System for Rice Disease Identification and Control Recommendation
## 4 RiceMan Application Development
### System Requirements  
Figure 3 depicts the use case diagram of RiceMan, covering three groups of target users: farmers, agronomists, and scholars. Firstly, farmers can use RiceMan to understand possible causes and suitable treatments for their plants. However, according to the discussion with agronomists, many traditional farmers in Thailand prefer to consult with agronomists. Thus, we consider agronomists who are responsible for supporting farmers to seek suitable treatments as the second target group. They need to understand the relationship between abnormalities and diseases and the relationship between diseases and treatments quite well. Without intelligent tools, they need to memorize all complex relationships to support farmers. Although the domain knowledge covers 18 diseases, its search space is complex since any disease can be indicated from various combinations of abnormalities: 28 colors, 11 shapes, 29 symptoms, 24 plant parts, and 5 growth stages. While RiceDO's disease axioms do not contain all combinations, a particular disease could contain up to 15 combinations. Hence, RiceMan advances agronomists' working methods by offering intelligent functionalities about diseases and treatments. RiceMan provides a more reliable approach than utilizing solely offline documentations. Lastly, scholars use RiceMan to support their activities. Since RiceMan identifies diseases based on observations and suggests treatments based on the identified diseases, then students and researchers can utilize this functionality to simulate specific scenarios for their study and research. The reasoning capability equipped with RiceMan is a perfect tool for this purpose. Important use cases of the system are explained as follows:  
* **Add observations:** upon the finding of abnormal appearances on a rice plant, a user can use RiceMan to create observation data digitally that represents the observed abnormal appearances.
* **Find possible diseases:** to find possible diseases, both explicit and implicit diseases corresponding to an observation, RiceMan employs logical reasoning to consider the logical relationships defined in RiceDO for the identification.
* **Compose observations (with respect to a distance and a duration):** concerning the fact that some rice diseases and paddy insects are spreadable to nearby areas, a user may choose to include observations made within the specific distance and duration in his/her consideration of the disease diagnosis. This functionality is called the _observation composition_. It calculates the distance between different latitudes and longitudes and considers the duration in the unit of days.
* **Find possible transmittable diseases:** once users consider composing observations, the identified results can be classified into (1) possible diseases with respect to distance and duration; and (2) possible transmittable diseases, with respect to distance and duration.
* **Find possible controls:** RiceMan considers possible controls for a disease based on the knowledge defined in TreatO by an employment of logical reasoning.
* **Find possible abnormalities of a given disease:** RiceMan can return all possible abnormal appearances on a rice plant if it is infected by a particular disease. This enables users to compare their observations with the retrieved results and make a better decision.