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[railML3] Restricting aggregation of RailTopoModel [message #3237] Mon, 29 April 2024 17:13 Go to next message
Larissa Zhuchyi is currently offline  Larissa Zhuchyi
Messages: 62
Registered: November 2022
Member
Dear all

railML.org suggests to introduce new semantic constrains to make aggregation model less ambiguous and easy to read. Please review the suggested semantic constrains IS:008, IS:009 and IS:011 and provide your comments.

All the three semantic constrains seem to be imposed by RailTopoModel and can not be implemented in XSD, which is consistent with the guidelines on the introduction of semantic constrains of railML.org [1]. Furthermore they occurred in the example data provided by the railML.org partners.

Suggested semantic IS:008 constraint for railML3.
Aggregation of net elements should follow the tree data structure. See figure [2]. This means that no two (mesoscopic) net elements can aggregate same (microscopic) net element. In other words, (microscopic) net element can be aggregated by at most one (mesoscopic) net element.

Suggested semantic IS:009 constraint for railML3.
Linear (geometric) coordinates (explicit or implicit, e.g. calculated as a sum of the coordinate of beginning and the length of the net element) of the same place represented at different levels of aggregation should have the same value. In the figure [2] (linear) coordinate the coordinate of e.g. end of ne1 should be same as one of ne1.2.

Suggested semantic IS:011 constraint for railML3.
Aggregation must not happen within the same level of detail. In the figure [2], element 1.1 must not aggregate element 1.2. This means that aggregating and aggregated net elements must not be referred from the same <level>.

Thanks in advance.

[1] https://wiki3.railml.org/wiki/Dev:Semantic_Constraints
[2] https://wiki3.railml.org/wiki/IS:netElement

Sincerely,

Larissa Zhuchyi – Ontology Researcher
railML.org (Registry of Associations: VR 5750)
Altplauen 19h; 01187 Dresden; Germany www.railML.org

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Re: [railML3] Restricting aggregation of RailTopoModel [message #3258 is a reply to message #3237] Fri, 21 June 2024 13:20 Go to previous messageGo to next message
christian.rahmig is currently offline  christian.rahmig
Messages: 503
Registered: January 2016
Senior Member
Dear railML community,

as there have been no reactions so far, I assume that you all agree with the proposed semantic constraints on aggregation of topology.
If that conclusion is not correct, please let us know your feedback and ideas, so that we can incorporate them in the development of upcoming railML 3.3.

Thank you very much and best regards
Christian

Christian Rahmig – Infrastructure scheme coordinator
railML.org (Registry of Associations: VR 5750)
Altplauen 19h; 01187 Dresden; Germany www.railML.org

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Re: [railML3] Restricting aggregation of RailTopoModel [message #3531 is a reply to message #3258] Fri, 28 March 2025 11:10 Go to previous message
Milan Wölke is currently offline  Milan Wölke
Messages: 178
Registered: April 2007
Senior Member
Hi Larissa and Christian,
I would strongly recommend to find a wording for these semantic constraints that can stand on its own. The figure currently referenced by the proposed wording is a good idea, but should be part of the general documentation and not used as a base for the semantic constraint. If the figure changes the semantic constraint would change. Also the word should is not suited to express the constraining characteristics of a semantic constraint. I would recommend the following wording:

IS:008
When aggregating net elements each net element of a lower level of aggregation shall only directly belong to a single net element of a higher level of aggregation.


IS:009
When aggregating net elements neither linear nor geometric coordinates given on a lower level of aggregation shall contradict the coordinates given for the aggregating net element on a higher level of aggregation


IS:011
Aggregation must not happen within the same level of aggregation. No net element of a certain level of aggregation shall be part of another net element on the same level of aggregation.


Best regards, Milan

Milan Wölke – Timetable scheme coordinator
railML.org (Registry of Associations: VR 5750)
Altplauen 19h; 01187 Dresden; Germany www.railML.org

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