12-semi-lattic-folksnomy

Someone sent me this problem statement.

While I still don’t understand what the author meant, if you choose to classify elements in the set with folksnomy, you can keep elements in a semilattice structure made out of tags. It is technically a full lattice, but we only need to go up.

Initially, every element has no tags and start at the bottom. When an element is given a new tag, it is moved up to the corresponding lattice point.

You build this lattice dynamically.

Every lattice point keeps a linked list of elements with that set of tags. The first one in the list can be the canonical element of that set of tags.