copycat82 Gate: Either Waste, or Lost
to paint E-net (or SARA) nodes, with Petri nets

The Petri net primitives, places vs. transitions, serve different needs. Places fork and join alternative-paths, whereas transitions fork and join synchronized paths.

To imitate E-nets, or SARA, it is trivial to employ macro-transitions or macro-locations. To provide that uniformity, with only macros, is a bit of waste, though. e.g: the "and" (J-transition) macro, would necessitate an extra pair of place-transition, even to express ordinary join-fork. This is three elements, where one would suffice.

The specification versus the implementation of copycat82 commit a self-contradiction. i.e: In words, it is as if E-nets, but implemented as if (unwasted) Petri nets. Maybe to avoid that waste, copycat82 assumes only a transition would suffice (p.129), although that leaves the words unimplemented. Without an extra place for an "input-and," where would the immediately removed" token stay, after the subnet is enabled?

VD78 and Pe77 do not waste any net element. They use the Petri net formalism, as it is. This is the difference, when copycat82 is any different, at all. Otherwise, to name a place as "XOR-output" or as "input-++" would not present any new idea, for a Petri net. When these appear as if, at a transition, that may appear as "different." But is it wanted? It is only a preference of the UCLA-graphs primitives, over the Petri nets.

As such, copycat82 is also similar to the SARA CFA strategy, when it paints the graphs with UCLA input/output operators, and next, attempts to verify as Petri nets. But the (false) assumption of separately-verifiable macros, suggests copycat82 imitates VD78, about the verifier strategy.

It overall, represents imitative of E-nets, paints and gives examples imitative of SARA, and attempts to verify imitative of VD78. And when we compare with SARA CFA, copycat82 also lacks the extras of SARA CFA. e.g: macro-expansion (without which copycat82 is absurd to verify), and lack of control-states-reduction (which increases the importance of any waste).

Further Reading

The plagiarism of copycat82 encompasses its input-gate, and its output-gate, too.

The implementation of "++ input" is, emphatically, imitative of VD78 Fig.4, with a copycat82-ignorance about, subnets versus (instantaneous) transitions.

Rewrote With Other Words ...

input/output macro quirks

The "and-paths" and "single-path" are the ordinary Petri net entrance/exit, but copycat82 is problematic even there. (It is either expensive, with an unnecessary extra step, or it appears as if tokens get lost, while the subnet is busy.

The other entrance-macros (static snapshots of Y-transition), contain their own problems. With Petri nets, alternatives diverge/converge at places. i.e: This is easy with VD78, any way.

Tokens at large?
Where does a token go, when a subnet is busy?

There is mismatch between the no-macro-at-entrance case, and four of the macros, in expected token-draw behavior. The "and" is both ways. It is specified to remove a token, immediately after the execution starts (pp.45-46). This is similar to the macros, but the implementation (on page 129) does suggest not-to-do-it, because in such a case, while that subnet is yet to finish, no token would be visible in the net. The "and" does not have any extra-place before it. Alternatively, if there were any extra places, to be similar to the other macros, it would be a needless expense, in terms of useless places, as compared to ordinary Petri nets, which do the same job. Whatever the case for "and," the case with entrance-macro, versus without such macros, is either way, chaotic. Does a token stay before the subnet, or does it get lost, when a subnet is started, until it is finished?

In other cases, some input-macros may have "internal" places, whereas some other cases omit any. Next, when copycat82 refers to "token drawn immediately," such variations make the sentence either vague, or absurd. (This is the conflict between Petri net vs. E-net/SARA primitives/nodes)

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Referring#: 0
Last-Revised (text) on Nov. 26, 2004 . . . that was
mirror to, on June 17, 2009
Written by: Ahmed Ferzan/Ferzen R Midyat-Zila (or, Earth)
Copyright (c) 2004, 2009 Ferzan Midyat. All rights reserved.