Date Range Overlap with Nullable Dates

Question

I\'m looking for an extended answer to the question asked here:

Determine Whether Two Date Ranges Overlap

where any of the dates in either date range can be null

Answer 1

That is probably as 'simple' as you can get it, although I haven't actually proven it.

It probably isn't worth it to simplify further, since that block ends up being about 8 operations in the worst case (4 on average thanks to short-circuit evaluation).