Set function to check for intersection?

[eschnett]

When dealing with sets, one often needs to check whether two sets have a non-empty intersection, but the intersection itself is not interesting. This can currently be written as isempty(a ∩ b), but this is likely much less efficient. There should be a function that checks for intersection, returning Bool.

What would be a good name for this? Python uses isdisjoint.

[JeffBezanson]

Seems like a good idea, and a decent name. This seems to be one of those weird cases where the only word for something is negative; you can be "disjoint" or even "nondisjoint" but not "joint".

[eschnett]

You can be "intersecting", so isintersecting would also work.

However, if you allow three sets as arguments, the meanings differ -- isdisjoint implies they are all disjoint, whereas isintersecting implies they are all intersecting, thus they are not opposites. (This is relevant since Base has multi-argument methods for intersect and union.)

[StefanKarpinski]

It depends on if you mean pairwise disjointness and pairwise intersection or not.

[rfourquet]

Fixed in #34427.