[Om] Tutorial or example collection for OpenMath?

[Konrad Hinsen]

Alberto González Palomo writes:

 >    Hi, I made long ago a formula editor with symbol palettes that you
 > could use to find the OM encoding of common formulas, although
 > most likely you would have to tweak them afterwards by hand.
 >    I've dusted it off and made a little application that shows you the
 > OpenMath and MathML source as you modify the formula:
 > 
 > http://matracas.org/sentido/demo/index.xhtml
 > 
 >    Please note that it works only in Firefox!

Thanks, that looks very useful indeed!


Lars Hellström writes:

 > One resource I've found useful is the "Index of all symbols" 
 > (http://www.openmath.org/cdindex.html). Searching in this page has a good 
 > chance of turning up something relevant, even if it's in a content 
 > dictionary you didn't expect.

That's a very good resource as well, thanks!

 > As for encoding a sum over all pairs of indices, there is the
 > complication that the official OMCDs aren't fond of expressing
 > things using binder symbols (even if the standard supports the
 > concept of such), so one typically has to wrap the body up in a
 > lambda before feeding it to a summation symbol; sort of like
 > writing $\sum_{[a,b]} f$ rather than $\sum_{k=a}^b f(k)$. Thus we
 > get

Thanks for the example. That's in fact the kind of information I was
looking for: general design principles that help finding the right way
to express things.

For the particular case of "sum", I find the definition in arith1 a
bit vague:

   An operator taking two arguments, the first being the range of
   summation, e.g. an integral interval, ...

There is no definition of "range of summation", just an example. You use a
set in your example, which is fine, but there's nothing in the definition
of "sum" that tells me that sets are a valid specification for a "range of
summation".

Which leads to another question: is there any validation tool for
OpenMath that checks the semantics? The XML schemas and the XSLT
stylesheet from the OpenMath Web site only check syntactical aspects,
they won't stop me from using transc1/sin as a summation range, for
example.

Konrad.