M. Holcombe: X- machines as a basis for dynamic system specification, Software Engineering Journal 3, 1988, 69-76.  Home/Search   Document Not in Database   Summary   Related Articles   Check

.... to test the implementation ( 6] Where there is a formal specification or model, this may be used as the basis of test automation (see, for example, 5, 8, 11, 10, 12] One approach, to formally specifying a system, is to use a form of extended finite state machine called a stream X machine ([13, 14, 3, 17, 2, 15, 18, 1]) A stream X machine describes a system as a finite set of logical states, each with an internal store or memory, with transitions between the logical states. A transition is triggered by an input value, produces an output value and may alter the internal store and logical state. A stream ....

M. Holcombe. X-machines as a basis for dynamic system specification. Software Engineering Journal, 3:69--76, 1988.

....mechanism as a formal specification model. Keywords: generalized stream X machines, formal grammars, cooperating distributed grammar systems, Turing machines, computational models 1 Introduction Introduced by Eilenberg in 1974, 6] X machines have received little further study. Holcombe, [7], proposed the model as a basis for a possible specification language and since then a number of further investigations have demonstrated that this idea is of great potential value for software engineers. In its essence an X machine is like a finite state machine but with one important ....

.... also of practical interest when some specifications may naturally lead to some simple grammars that define the set of all legal input strings that should be processed[8] In the last part of this paper is provided an example showing how the set of legal input strings submitted to a scanner system [7] may be specified by some suitable grammars which gives the production rule components of a generalized stream X machine with underlying distributed grammars. 2 Basic definitions and examples For a set Q we denote by 2 Q the family containing all subsets of Q: Let Sigma be a finite alphabet; ....

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M. Holcombe, X- machines as a basis for dynamic system specification, Software Engineering Journal 3, 1988, 69-76. 17

....subject to assumptions about redundant states, by driving the system through its transition cover and comparing all valid and error states reached with the specification. Rigorous Object Oriented Methods, 2000 1 On the Compositional Properties of UML Statechart Diagrams Holcombe and Ipate [10, 11, 12] have generalised this approach for Stream X Machines, which are a generalisation of finite state machines with a global memory and input output streams. X Machines are formally equivalent to a restricted class of augmented transition networks and have Turing equivalent computing power. Using the ....

Holcombe W M L. X-machines as a basis for dynamic system specification. Software Engineering J 1988; March:69-76

....the real time aspects of CXMs. The real time communicating X machine (CXM) is an extension of the communicating X machine model which, in turn, is an extension of the stream X machine model. The stream X machine (Laycock, 1993) is a typed finite state machine for modelling sequential systems, (Holcombe, 1988, Barnard, 1993) A CXM models a process as a timed typed finite state machine. Each CXM is able to communicate with other CXMs through its output windows and input ports. Communication between two CXMs is established through the use of a named channel which connects a window of the sending CXM to ....

Holcombe M., 1988, X-machines as a basis for dynamic system specification, Software Engineering Journal, March 1988.

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M. Holcombe: X- machines as a basis for dynamic system specification, Software Engineering Journal 3, 1988, 69-76.

....considered in this context. 1 In this approach are combined two models, CDGS [17] and X machines [9] developed as topics in the frame of formal language theory and applied in artificial intelligence [8] 16] the former , and in formal specification and verification of complex software systems [10], 11] the later . Some common properties of these models have been taken into account for this approach [8] ffl the information needed to solve a problem is partitioned into separate and independent knowledge sources (set of rules for CDGS and the relations functions for X machines) ffl ....

M. Holcombe: X-machines as a basis for dynamic system specification, Software Engineering Journal, 3(2), 1988, p.69-76.

....CDGS, k; k; k; and t [7] are considered. Our approach combines two models, CDGS [16] and X machines [8] developed as topics in the frame of formal language theory and applied in artificial intelligence [7] 15] and for the formal specification and verification of complex software systems [9], 10] respectively. 2. Basic definitions For a set Q we denote by 2 Q the family containing all subsets of Q: Let Sigma be a finite alphabet; Sigma is the set of all strings having symbols from Sigma. By we denote the empty string. The length of a string s is denoted by j s j : Let P ....

M. Holcombe: X-machines as a basis for dynamic system specification, Software Engineering Journal, 3(2), 1988, p.69-76.

....may partly define the meaning of several operations and a single operation be wholly defined by several axioms. Algebraic approaches, though powerful, have gained limited acceptance outside the research community. As an alternative to formal specification, state machine based modelling approaches [Schu87, Holc88, Cook94] have increasingly been adopted, especially variants of Statecharts [Hare87, Hare96, Hare97, OMG99a, OMG99b] a semi formal design notation, and more formal models of labelled transition systems [Miln80, Hoar85, Miln89, Miln99] related to process algebras. The notion of model checking is based on ....

....to profit fully from this, page 3 because they synthesize large, flat state machines for the entire system [Bind96, Kim99] and so may reach the limit of what is feasibly testable, due to the millions of states and paths. A hierarchical state specification approach was first advocated by Holcombe [Holc88], based on Eilenberg s X Machine [Eile74] a finite state machine with transition functions operating on a shared memory. The advantage of this model lies in its ability to abstract over functions of arbitrary complexity at one level and later expose them as independent state machines. Subsequent ....

WM L Holcombe, X-machines as a basis for dynamic system specification, Software Engineering J., March, 69-76, 1988.

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