Indeed, that would help in this example. For more complicated
examples, there may be combinatorical effects when "desugaring" the
partial NAC into several standard NACs. It's an interesting question
if one could give an algorithm for doing that. Maybe something to
tackle under the Christmas tree. :-)
Best regards,
Daniel
On 12/20/2019 11:41 AM, Zschaler,
Steffen wrote:
Thanks. But
one could express this by adding a second NAC that extends
the right B with a D.
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
In the context of the alternative semantics (which, as we
figured out in the other sub-thread, currently isn't
implemented), I think it still would make a difference. I put
a slightly modified version of the example below. The only
difference is the inclusion of an additional "forbid" element,
which is connected to the existing "forbid" element via an
edge.
[forbid :D] --> [forbid :B] ---> [preserve :A]
<---- [preserve :B] <----- [create :C]
The "border-elements only" NAC looks like this:
D -> B -> A (where A has a mapping from the
LHS)
The "replicate full LHS" NAC looks like this:
D -> B -> A <- B (where A, the right-hand B,
and their common edge have mappings from the LHS)
An example model where a rule including either of these NACs
would match:
b:B -> a:A
An example model where a rule including the second NAC, but
not the first NAC would match:
d:D -> b:B -> a:A
Best regards,
Daniel
On 12/20/2019 11:21 AM, Zschaler, Steffen
wrote:
Sure, but
then it wouldn’t make a difference whether we use a
complete or incomplete morphism, would it?
Many
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
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.
Best regards,
Daniel
On 12/19/2019 3:06 PM, Zschaler,
Steffen wrote:
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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Chalmers | University of Gothenburg, Sweden
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Department of Computer Science and Engineering
Chalmers | University of Gothenburg, Sweden
http://danielstrueber.de/
_______________________________________________
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To change your delivery options, retrieve your password, or unsubscribe from this list, visit
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--
Dr. Daniel Strüber
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Department of Computer Science and Engineering
Chalmers | University of Gothenburg, Sweden
http://danielstrueber.de/
_______________________________________________
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henshin-user@xxxxxxxxxxx
To change your delivery options, retrieve your password, or unsubscribe from this list, visit
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--
Dr. Daniel Strüber
Postdoctoral Researcher
Department of Computer Science and Engineering
Chalmers | University of Gothenburg, Sweden
http://danielstrueber.de/
_______________________________________________
henshin-user mailing list
henshin-user@xxxxxxxxxxx
To change your delivery options, retrieve your password, or unsubscribe from this list, visit
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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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