Re: containers: intersections for Set, along with Semigroup newtype

On Mon, Dec 21, 2020 at 02:06:33PM -0800, David Casperson wrote:

Lattices aren't necessarily isomorphic to their duals, even with bounded lattices. (Take, for instance, lcm and gcd on the non-negative integers. The primes are atoms, there are no co-atoms. [1])

But the non-negative integers with gcd and lcm are surely not a bounded lattice. If we introduce an upper bound by restricting attention to numbers that are factors of some number n > 1, then surely co-atoms reappear in the form of n/p for each prime factor of n. -- Viktor.