 (6) presupposes that there is a king, (7) that there is a king and that the king has a son. (8) contains both (6) and (7). It seems to inherit the presupposition of (6) but not of (7); that is, (8) presupposes that there is a king, but not that he has a son. A correct theory of just how presuppositions are inherited from simple to complex sentences would solve the projection problem, and doing so seems to be required for a semantic account of presupposition. A number of interesting theories have been put forward; it is not our purpose to claim that they are or are not successful. (See Karttunen 1973, 1974; Karttunen and Peters 1979; Gazdar 1979; Soames 1989; Burton-Roberts 1989a-b, 1999; Heim 1992; Horn 19995; Asher and Lascarides 1998; Carston 1998, 1999a; Kamp 2001; Beaver 2002; Schlenker 2010.)