Per my earlier question I'm trying to find a reasonable metric for the semantic distance between two short text strings. One metric mentioned in the answers of that question was to use shortest hypernym path to create a metric for phrases. So for instance, if I was to find the semantic distance between pig and dog, I could ask WordNet for all of their hypernyms:
pig=> swine=> even-toed ungulate=> hoofed mammal=> placental mammal=> mammal=> vertebrate=> chordate=> animal=> organism=> living thing=> object=> physical entity=> entity
dog=> canine=> carnivore=> placental mammal=> mammal=> vertebrate=> chordate=> animal=> organism=> living thing=> object=> physical entity=> entity
and I would find that the shortest path between pig and dog is 8 jumps - so semantic distance = 8.
If I wanted to extend this concept to entire phrases, then perhaps I could (naively) find the average distance between all word pairs in the phrases. (Obviously, one should be able to find something much better than this.)
My question: I'm sure someone has thought of this before. Where should I look in literature to find more information. And what are the hidden gotchas when using such an approach.