Như một ví dụ chi tiết, hãy xem xét quá trình trừu tượng Cung cấp khách hàng Sắp xếp trong hình 4a, mà có thể được tinh chế thành hai quá trình khác nhau trong hình 4b và c. Hai quá trình tinh chế có trạng thái ban đầu giống hệt nhau và cuối cùng, thứ tự khách hàng mở và Lệnh Giao khách hàng, tương ứng, cũng như quá trình trừu tượng. Tuy nhiên, trong khi hình 4. Một mô hình trừu tượng và hai cải tiến có thể. | On the Use of Object-Role Modeling for Modeling Active Domains 133 assume an environment E for evaluation consisting of a partial assignment of values to a set V of variables. The standard semantic interpretation of the temporal operators is as follows for lack of a typographic alternative we use the symbol here for is defined as. M E o Xọ M E oi ọ M E o ọ Uy 3 vo í n M E o 7 ọ A M E o n y where o 7 denotes the ith element of sequence o and o the subsequence of o starting at position i. The other temporal operators are defined in terms of these base operators Fọ is equivalent with true ọ Uy and Gọ is defined as F ọ. The propositional operators are also interpreted in the standard way M E o ọ M E o qAy M E o ọ M E o ọ A M E o y. The constant false is introduced as pA p where p is any proposition from n and true is derived by false. The other logical operators v and are defined in the usual way. The conversion from a temporal proposition to a static expression requires the evaluation of the static expression for the population L o 0 at the required point in time. This will be further elaborated later. Historical Information Descriptors History descriptors in ORC are meant to provide a language construct for reasoning about the application domain in a historical setting. For the purpose of this chapter it will be sufficient to make direct transcriptions of the basic temporal operators. For this the syntactical construct of history descriptor is introduced. Let H be a history descriptor then the semantics of H are denoted as H always H - G H X H - X H . Copyright 2007 IGI Global. Copying or distributing in print or electronic forms without written permission of IGI Global is prohibited. 134 van Bommel Hoppenbrouwers Proper van der Weide In addition we introduce the following abbreviations sometimes H H1 precedes H2 H1 during H2 H1 triggers H2 always H always FH1 U H1 always H1 H2 always H1 A H X H1 A H2 We will now introduce some example rules that match a more .
