Schelling points and enthropy of human mind

Hi, Tim May presented an interesting concept of two persons who want to meet in Washington DC but forgot to decide where to meet. He says that they will likely to be in only several places and that such places will be "points of low enthropy". The question is, how do you define "enthropy" in this case? Also, for a while I've been thinking about enthropies of cultures and individuals. I wonder if anyone knows any books or theories that define such things. - Igor.