  There are other views that deviate from the above standard definitions of possibilism. Carlson (1995: 99–109; 1999) defends a view that bears resemblance to possibilism in which the sole obligatory act-set is a unique minimally specific invariably optimal act-set. At t an act-set is optimal for an agent S just in case its outcome is at least as good as any other act-set that is performable for S at t. An invariably optimal act-set is one which is optimal no matter what S does at t. An invariably optimal act-set is minimally specific just in case it is not a proper part of some other invariably optimal act-set available to S. A minimally specific invariably optimal act-set is unique just in case there is no other minimally specific invariably optimal act-set available to S. Thus, in contrast to standard formulations of possibilism, no act-set that is a proper part of a unique minimally specific invariably optimal act-set has a deontic status. Vorobej (2000) defends a view he refers to as “prosaic possibilism”, which may be considered an intermediary between possibilism and actualism. In his (2009) article, which contains an argument against possibilism, Woodard defines the view in terms of normative reasons for action rather than moral obligations. As a final example, in his (2016) article, Vessel proposes what he takes to be a “possibilist variant” of a view known as moral securitism, which will be discussed in  section 4.  The first possibilist definition given in this section, however, captures the standard understanding of possibilism and the commitments of its proponents, including Greenspan (1978), Thomason (1981), Humberstone (1983), Feldman (1986: 38), and Zimmerman (1990; 1996: 190; 2006; 2008: ch. 3; 2017). On this definition, Procrastinate is obligated to agree to review the paper since it is part of the best series of acts that she can perform over the course of her life.