Re: SHACL complexity

Thanks for the feedback; and I'm really sorry that I couldn't join the call
on Monday due to a last-minute engagement that came up.
I'll make sure to attend the meeting on 31 Mar.

I'd be happy if:

   - People give some thought to the complexity implications of various
   features
   - Potentially, we define some modest profiles with known low complexity

I believe that there are some sweet-spot features that are both important
in their own right, and low complexity.
Namely, a *SHACL-for-modeling* subset that doesn't include boolean
operations, complex paths, complex node expressions, or complex sh:node
invocations.
"The 20% of features used 80% of the time".

Coupled with some guidance or ontology concepts on how to structure shapes.
https://github.com/w3c/data-shapes/issues/242 is one such example:

   - full shape (for checking all props) vs
   - reference shape (for checking existence and "business type"
   conformance)