Yes, in this example, the rule would be inapplicable. To
slightly modify the example to get two applicable rules, we
may include some additional "forbid" elements (without a
counterpart in the LHS) into the original rule.
Just to
make sure I understand this correctly:
-
When only the
border elements are replicated in the NAC (here: the :A
node), the NAC looks like this:
-
B ->
A (where A has a mapping from the LHS)
-
Wouldn’t
that mean the rule can simply never be matched (because
there would, by definition always be a B to be matched for
the NAC)?
Steffen
Dr. rer. nat. Steffen Zschaler AHEA
Senior
Lecturer
King's
College London
Department
of Informatics
Visiting
Scientist
The
Francis Crick Institute
Email
szschaler@xxxxxxx
Phone
+44 (020) 7848 1513
WWW
www.steffen-zschaler.de
Consider a rule (using the integrated syntax:)
[forbid :B] ---> [preserve :A] <---- [preserve
:B] <----- [create :C]
When only the border elements are replicated in the NAC
(here: the :A node), the NAC looks like this:
B -> A (where A has a mapping from the LHS)
When the full LHS is replicated, the NAC looks like this:
B -> A <- B (where A, the right-hand B, and
their common edge have mappings from the LHS)
Using the first NAC, the forbid node can be matched to all
:B objects from the input model, including one which was
bound to the preserve :B node while matching the LHS.
Using the second NAC, the forbid node cannot be matched to
a :B object which was already bound by LHS :B node.
Best regards,
Daniel
On 12/19/2019 2:15 PM, Zschaler,
Steffen wrote:
Thanks,
Daniel. You seem to imply that there is a semantic
difference between the three forms. Could you explain?
Thanks,
Steffen
Dr. rer. nat. Steffen Zschaler AHEA
Senior
Lecturer
King's
College London
Department
of Informatics
Visiting
Scientist
The
Francis Crick Institute
Email
szschaler@xxxxxxx
Phone
+44 (020) 7848 1513
WWW
www.steffen-zschaler.de
Hi Steffen,
Henshin allows the morphism between
the host graph and the application condition graph to be
a partial morphism. Consequently, all three cases you
mention (only nodes replicated, only border nodes
replicated, full LHS replicated) would specify different
application conditions for the same rule.
While this design decision has its
awkward sides (especially the representation in the
graphical editor), I encountered some situations before
where it was desirable, as it allowed to precisely
specify an intended behavior.
I'm actually surprised by the fact that
the graphical editor defaults to the "node only" case -- I
would have expected "full LHS replicated" as the default.
However, in most cases, the resulting behavior will be
identical. The only exceptions seem to arise in the
(exceptionally rare) case where there are multiple
references of the same type between the same two objects.
On 12/19/2019 11:32 AM, Zschaler,
Steffen wrote:
Hi,
A rather technical question about NestedConditions
and their
representation in a .henshin file. Do tell me to
take this somewhere else if that would be more
appropriate.
I understand the theory behind
application conditions: the condition is a graph and a
morphism into this graph from a host graph. That is
represented in Henshin by the ability to add a “formula”
to a graph, where this formula can be a
NestedCondition,
which itself again contains a graph and a set of
mapping. The containing graph is the host graph, the
graph in the
NestedCondition
is the application-condition graph, and the mappings
capture the morphism. So far so clear.
Except that’s not how it seems to
work in practice: if you look at the attached file,
produced by the standard graphical editor, you will see
that only the
nodes from the host graph have been replicated in
the application-condition, but the
edges haven’t. In other examples, I have seen
cases where only the border nodes had been replicated.
In any case, the mappings clearly aren’t a morphism as
they do not fully cover the host graph.
Are all of these formats indeed
acceptable? If so, is there a regularised format that is
used inside Henshin and, if so, can this be reused
outside of Henshin? Alternatively, are there minimum
expectations on how an application condition should be
encoded in a .henshin file? Is any of this documented
anywhere? Should it be?
Thanks,
Steffen
Dr. rer.
nat. Steffen Zschaler AHEA
Senior Lecturer
King's College
London
Department of
Informatics
Visiting Scientist
The Francis Crick
Institute
Email
szschaler@xxxxxxx
Phone +44 (020)
7848 1513
WWW
www.steffen-zschaler.de
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--
Dr. Daniel Strüber
Postdoctoral Researcher
Department of Computer Science and Engineering
Chalmers | University of Gothenburg, Sweden
http://danielstrueber.de/
_______________________________________________
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--
Dr. Daniel Strüber
Postdoctoral Researcher
Department of Computer Science and Engineering
Chalmers | University of Gothenburg, Sweden
http://danielstrueber.de/
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