Ready.

Page 69. This page is in the page-by-page raw-dumps section.



Fig.3.8 Messing the Programming Language Semantics.

The figure 3.8 has four parts, and the caption reads "The representation of ordinary statements." The first one is a wishful, and untrustable, implementation of sequential-execution of three components. The other three are using "xor-out", which corresponds to the X-transition of E-nets, and this is one of the points, it is being like Danthine (1980), in using X-transitions, in a Petri net context.

None of the data-in rectangles, for the decision, pointing to an "xor-out ("X-transition), on these two pages 68-69, have any incoming arcs, and this again, looks like E-nets resolution location, for an X-transition (as in all the cases on the pages 68-69). (The data-out arcs are an ephemeral consequence, of the merging of the data-flow graph of ValDia78, into its Petri net (control) graph. Then, the copycat82 merges E-nets, with ValDia78, although it does not cite so. The word ephemeral, is about the data-sharing links being torn-apart in the internal levels, and they are useless duplicates, practically at any level, as they must be corresponding to some places that show the data-sharing. In fact, the copycat82, similar to E-nets associating token-attributes with the tokens, states (on p.36) that a data item is associated with a place. (It is the places that hold tokens. The E-nets likeness is full). And then, the data are pointing to/from transitions/subnets, again, as in the case of E-nets.

The "resolution procedure" of E-nets is renamed "data-dependent (input/output) control transfer specification", (X-transition is output, Y-transition is input, as the shape Y already suggests, two input, one output) and the "transition procedure" of the E-nets have been renamed "data-transfer specification" The enabled-with-tokens, for all (T-, J, F-, X, Y-) transitions, have been renamed "control-independent [input/output] transfer specification" Is that the contribution? Only renaming, without any new abstractions/improvements. The content comes from Danthine (1980), and some introductory computer science texts. And that happens to be awarded a Ph.D. title. Is that a joke?

as weel as for X-

Fig.3.8.a What sort of Sequential Enabling/Execution is that?

The figure has four parts. The Fig.3.8.(a) expects us to believe that the caption "S1;S2;S3" corresponds to the figure, which are only three rectangles, following each other. It would only be true if those rectangles were, instead, ordinary Petri net transitions. But when they are "components" as defined in the copycat82, and when we look at the definition of the ";" operator, in a later figure, even total reversal in the sequence is possible. This figure, as a result, only proves us that even the Ph.D. grantee does not understand that the macro he defines can reverse the firing order. (That definition is also repeated in the copycat83, a year later.)

Fig.3.8.d Do not Touch That Button! Oh no!

Fig 3.8.d, is supposed to be a case statement like Pascal language. But the given "case statement" semantics may exclude only adjacent selections, from each other. That is, S1 and S2 cannot be both occurring. Likewise, for S2 and S3, but S1 and S3 presumably could both fire together. What semantics is this?

An argument is imaginable that "a parantheis is missing" but I preferred to make this argument explicit. The copycat82 is full of faults, and this one may appear unimportant. But when the given text is a dissertation in "... designing and analysing of distributed software systems", and if a missing paranthesis may lead to some adverse consequence(s), how to ignore it? If two Ph.D.s )the nominee, and the figure-drawing person), plus their advisors, and the jury keep missing all such "minor errors," with such side effects, how may we trust such a verbose (very crowded) visualism?





Further Reading

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