I've come across a rather interesting CS problem during work that I thought I'd throw out there. The problem is this: given a finite lattice (L, ⊑) (our problem has a lattice that is also distributive, so you may presume that) and a node x in that lattice, efficiently compute the set S ⊆ L = { y ∈ L : x ⊏ y ∧ ∄ z x ⊏ z ⊏ y }. This is well defined
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