Sober subspaces and the Skula topology

It often happens that one wishes to show that a certain subspace A of a given sober space X is sober. The following is a pearl due to Keimel and Lawson, which was mentioned to me by Zhenchao Lyu in July: the sober subspaces of a sober space are exactly its subsets that are closed in the Skula topology. Read the full post.