His analysis has to deal with the notion of context: he proposes to associate to a word a core semantic description (the fact that a "door" is an "aperture") and to add some additional features, which can be activated in context ("walk-through" is the telic role of a "door").
note that d(sell, \Sell) = d(\Sell, sell) = 1. h(f) = the set of ancestors of f .