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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