W. Wulf, R.L. London, and M. Shaw. Abstraction and verification in Alphard: introduction to language and methodology. Carnegie-Mellon University, Department of Computer Science, 1976.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....languages at different levels of abstraction. We have designed ZD after functional modeling languages used for describing physical devices at several levels of abstraction [6] We have formalized the change of abstraction levels by using the notion of representation functions from ALPHARD [10]. Each module in ZD mediates an explanation in some state description language (SDL) For any implementation choice, a function maps from the abstract language to the chosen concrete language. For example, for an array implementation of a stack, the high level (in terms of stack operators) ....

William Wulf, Ralph London, and Mary Shaw. Abstraction and Verification in Alphard: Introduction to Language and Methodology. In Mary Shaw, editor, ALPHARD: Form and Content, Computer Science Monograph, pages 15--60. Springer, 1981. 6

....that maintain state information, like stacks, queues, and so on, also have a persistent abstract state. A generic device implementation consists of a representation function and function implementations for the function specified in the device specification. A representation function (Rep) Wulf et al. 1981 ] formalizes the change of abstraction levels and, hence, SDLs. The entities specification, implementation and requirement are common in component oriented reuse approaches, because they make it possible to prove the correctness of a component at its construction time. In the next section, we ....

William Wulf, Ralph London, and Mary Shaw. Abstraction and verification in alphard: Introduction to language and methodology. In Mary Shaw, editor, ALPHARD: Form and Content, Computer Science Monograph, pages 15--60. Springer, 1981.

....so called representation FSM which captures the most important internal states as representation states or predicates together with an abstraction of implementation transitions. The corresponding FSM invariant is called representation invariant following the terminology of CLU [LG86] and Alphard [WLS76] Concrete (Sather code) Abstract (FSM model) Design FSM Class Interface Representation FSM Class body Interface Implementation Figure 3: Different views of object class behaviour. With this distinction, each design state corresponds to one or more representation states (i.e. vectors of values ....

William A. Wulf, Ralph L. London, and Mary Shaw. Abstraction and verification in Alphard: Introduction to language and methodology. Technical report, USC Information Science, University of Southern California, Los Angeles, USA, 1976.

.... the cost of analysis incremental in two senses: incrementally at a fine grain for example, on a statement by statement basis interactively with the user; and incrementally on a large grain because of the separation of interface and implementation, we can follow the intuition in Alphard [30], and analyze each implementation independently using interfaces as the basis for analysis. Our goal, then, is to provide a practical application of formal methods in building large, evolutionary software systems with large groups of people. 1.3 Research Contributions of the Inscape Environment ....

....exceptions) Thus, by specifying the semantics of the module interface and including pragmatic information, the designer can define precisely the meaning of a module and indicate ways in which it can be properly used. Our approach is based on that of Hoare s input output predicates [12] see also [18, 30]) but extended in two ways: a set of obligations is added to the set of postconditions to form a result of an operation; and multiple results are provided to allow the description of both normal and exceptional exits from the operation. We use this predicate approach in Instress rather than an ....

W. A. Wulf, R. L. London, M. Shaw. "Abstraction and Verification in Alphard: Introduction to Language and Methodology." IEEE Transactions on Software Engineering, Vol. SE-2:4 (December 1976). pp 253-265.

....these objects to build the system. We found the technology of formal specifications to be a useful source of information about how objects are meant to be used. Algebraic specification approaches (such as OBJ [6] and Larch [7] and input output predicate approaches (such as Hoare [10] Alphard [29], Dijkstra [3] and Anna [15] represent some of the ways in which a system builder might describe the semantics of system objects. Algebraic axioms are particularly apt for describing the relationships between operations and for indicating how these operations are meant to be used. Input output ....

W. A. Wulf, R. L. London, M. Shaw. "Abstraction and Verification in Alphard: Introduction to Language and Methodology", IEEE Transactions on Software Engineering, Vol. SE-2:4 (December 1976). pp 253-265.

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W. Wulf, R.L. London, and M. Shaw. Abstraction and verification in Alphard: introduction to language and methodology. Carnegie-Mellon University, Department of Computer Science, 1976.

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