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Abstract The Z specification language is now widely taught in universities [1]. However, many novices find that, although they may understand specifications written by other people, they are unable to produce their own, satisfactorily. One of the ,reasons is the ,lack of suitable ,tools for these novices to learn Z systematically. Another ,is the m...
Contexts in source publication
Context 1
... application window is sub-divided into two portions, the top portion is called the navigation menu area and the lower portion is called the workbench. Figure 1 ˝ is a schematic picture of VisualiZer. ...
Context 2
... next step is to click on that icon in order to switch the VisualiZer into a mode where the user can define all the associated elements of that free type. Figure 10 shows a free type ˝ called REPORT-SYS and its elements "ok" and "unknown". ...
Context 3
... defined data schema has associated sub-tasks to be performed. These ˝sub-tasks include defining attributes (states) and invariants as shown in Figure 11. The creation of an attribute is similar to the creation of compound type. ...
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... the name of the attribute and the function type (such as a partial surjection function) have been chosen, the completed attribute will be shown within the workspace. Figure 13 shows how a set attribute AllUsers 4 and a function attribute Password 5 are represented in VisualiZer. Note that the attribute "AllUsers" shown in Figure 13 looks very similar to the compound type "Department" shown in Figure 8. ...
Context 5
... 13 shows how a set attribute AllUsers 4 and a function attribute Password 5 are represented in VisualiZer. Note that the attribute "AllUsers" shown in Figure 13 looks very similar to the compound type "Department" shown in Figure 8. In the real application, they are differentiated by the colour of the title bar. ...
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... an attribute is used ˝for defining an ˝invariant, all the unary operators which are applicable to that attribute will be automatically listed inside the attribute. For example, in Figure 14, ˝ one could see that there are four unary operators namely: state after, count, dom and ran waiting for the user to select. Figure 14 also shows what has happened to the Password attribute after the domain operator has been selected. ...
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... example, in Figure 14, ˝ one could see that there are four unary operators namely: state after, count, dom and ran waiting for the user to select. Figure 14 also shows what has happened to the Password attribute after the domain operator has been selected. Note the change that has occurred at the title bar. Figure 14, the result of applying the domain operation ˝to the attribute Password will end ˝up in a set of PERSON. ...
Context 8
... the change that has occurred at the title bar. Figure 14, the result of applying the domain operation ˝to the attribute Password will end ˝up in a set of PERSON. Because this result is a set, it is possible to ˝apply another layer of unary operators to this set. ...
Context 9
... panel with a list of possible binary operators in which these two attributes can be applied will be enlisted together with graphical explanations. See Figure 16. ...
Context 10
... an operator is chosen, a larger window-like icon will encapsulate both the Password and AllUsers attributes together with the word "Subset" in between them. See Figure 17. ...
Context 11
... solve screen display problems, users can minimise both ˝ AllUsers and Password by clicking the minimise icon at the top left corner and the result is as shown in ˝ Figure 18. ...
Context 12
... an example, in Figure 19, the top portion of ˝the quantifier panel represents ˝the expression "x : PERSON. ...
Context 13
... procedures for creating new predicates within the scrollable area are exactly the same as for invariant's, but the scope of the predicates is only within the quantifier panel. The predicate expression in Figure 19 ˝ is X ¶ AllUsers. ...
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