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<p>Combining conceptual graphs with the task-based specification method to specify software requirements helps capture richer semantics, and integrates requirements specifications tightly and uniformly.</p> <p>Conceptual modeling is an important step toward the construction of user requirements. Requirements engineering is knowledge-intensive and cannot be dealt with using only a few general principles. Therefore, a conceptual model is domain-oriented and should represent the richer semantics of the problem domain. The conceptual model also helps designers communicate among themselves and with users.</p> <p>To capture and represent a conceptual model for the problem domain, we need</p> <p><li>mechanisms to structure the knowledge of the problem domain at the conceptual level, which has the underlying principles of abstraction and encapsulation; and </li> <li>formalisms to represent the semantics of the problem domain and to provide a reasoning capability for verification and validation.</li></p> <p>We propose the task-based specification methodology as the mechanism to structure the knowledge captured in conceptual models. TBSM offers four main benefits for constructing conceptual models: </p> <p>First, incorporating the task structure provides a detailed functional-decomposition technique for organizing and refining functional and behavioral specifications.</p> <p>Second, the distinction between soft and rigid conditions lets us specify conflicting functional requirements.</p> <p>Third, with TBSM, not only can we document the expected control flow and module interactions, but we can also verify that the behavioral specification is consistent with the system's functional specification.</p> <p>Fourth, the state model makes it easier to describe complex state conditions. Terminology defined in the state model can easily be reused for specifying the functionality of different tasks. Without such a state model, describing the state conditions before and after a functional unit of an expert system is too cumbersome to be practical.</p> <p>We propose conceptual graphs as the formalism to express task-based specifications where the task structure of problem-solving knowledge drives the specification, the pieces of the specification can be iteratively refined, and verification can be performed for a single layer or between layers. We chose conceptual graphs for their expressive power to represent both declarative and procedural knowledge, and for their assimilation capability--that is, their ability to be combined.</p>

L. F. Lai, J. Lee and W. T. Huang, "Task-Based Specifications Through Conceptual Graphs," in IEEE Intelligent Systems, vol. 11, no. , pp. 60-70, 1996.
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