 Kuusisto (2013) studies the expressive power of fragments of slash logic whose formulas are formed without employing the identity symbol. Kontinen et al. (2014) investigate the complexity-theoretic properties of the two-variable fragment of slash logic and compare this fragment to the corresponding fragment of dependence logic. Hodges (1997a,b) and Figueira et al. (2009, 2011, 2014) discuss an extension of slash logic in which the contradictory negation of slash-logic sentences can be expressed.