Seems that (a generalization of) the equation 1 in the paper by Toby Ord http://arxiv.org/abs/0810.5515 linked in the comments to Yvain’s post is something like what you are looking for.
This post is looking for salient examples of that type of behaviour.
Seems that (a generalization of) the equation 1 in the paper by Toby Ord http://arxiv.org/abs/0810.5515 linked in the comments to Yvain’s post is something like what you are looking for.
This post is looking for salient examples of that type of behaviour.