Add mathematical expressions

[Ludee]

Description of the issue

We want to evaluate on the possibility to add mathematical expressions to classes of the OEO.

Ideas of solution

• MathML

  • https://en.wikipedia.org/wiki/MathML#Example_and_comparison_to_other_formats
  • Even short formulas need to be adressed in XML-like long statements
  • Not all browsers support it

• LaTeX

  • looks easier and can be used directly in (scientific) documents
  • https://www.overleaf.com/learn/latex/Mathematical_expressions

Workflow checklist

• I am aware of the workflow for this repository
• Create a test branch with an example
• Run tests and break it
• Document and implement if needed

[Ludee]

I created an example document with 4 different latex options:
https://next.rl-institut.de/s/FNKac4DyqQtMBjb

There are two centered and two inline options.
Option 5 would be to only add the formula without the surrounding LaTeX expression.

[l-emele]

Nice example.

If we want LaTeX, we should avoid option 3 as the $ syntax is pure TeX and not LaTeX.

I like your mentioned option 5 as it is a) shorter and thus easier readable and b) easier for the users to build their own LaTeX arround that as needed.

Regarding your wind energy example: The notation is a bit ambiguous as it can also be interpreted as P= 1/(2 \rho A v^3). Therefore I would rather express this as P=(1/2) \rho A v^3 or P=\frac{1}{2} \rho A v^3.

[Ludee]

Thanks for the feedback.
I am currently adding a new annotation property called mathematical expression.
I would add this issue as term tracker item and a definition:

The mathematical expression is a property that describes the class with a mathematical formula.

[l-emele]

I would like to extend the definition a little bit: The mathematical expression is a property that describes the class with a mathematical formula in LaTeX syntax. (Or what ever syntax we finally decide on.) Else it is nowhere documented which syntax should be used.

[stap-m]

Nice! Just a further slight suggestion:
A mathematical expression is an annotation property that ...

[Ludee]

Looks like there is an issue that breaks the file in Protégée. #997
The underscores are translated with \\.

[Ludee]

In the OEO-DEV-31 we decided to solve this bug by using camel case for all variables in the expression.
Underscores and backslashes must be avoided.

[Ludee]

I wanted to document the result but wasn't sure where to put it. Should I create a new wiki page?

[l-emele]

A wiki page is a good idea. You can close then this issue imho with a link to the wiki page.

[Ludee]

Documentation is in the wiki:
https://github.com/OpenEnergyPlatform/ontology/wiki/Explanation-on-Annotation-Properties