 To fulfil these desiderata, Berto 2010 sketches an intermediate account, labeled as Hybrid Modal Realism (HMR), which dispenses with the Parity Thesis. The account follows suggestions from Divers 2002, Chapter 5, and is similar to a strategy pursued in Kiourti 2010, Chapter 3. On this view, genuine, concrete possible worlds are the basic stuff. Atomic propositions are taken as sets of possible worlds. Distinct impossible situations can then be represented by distinct world-books, taken as set-theoretic constructions from atomic propositions. Krakauer 2013 gives a similar account in terms of  structured propositions  built out of ordinary possible worlds. Jago 2012 and Sendłak 2015 criticise Berto’s approach on the basis that it cannot distinguish the proposition that Hesperus is the second planet from the sun from the proposition that Phosphorus is the second planet from the sun. Reinert 2018 attempts to do better by combining Lewisian possible worlds with an ersatz situation-based account of impossible worlds.