sentences:  In these logics, the concept of identity is restricted to some objects of the domain, and has motivation in Schrödinger's claim that the concept of identity does not make sense for elementary particles (Schrödinger 1952).Thus in order to provide a semantics that fits the logic, da Costa submitted that "a theory of quasi-sets should be developed", encompassing "standard sets" as particular cases, yet da Costa did not develop this theory in any concrete way.To the same end and independently of da Costa, Dalla Chiara and di Francia (1993) proposed a theory of "quasets" to enable a semantic treatment of the language of microphysics.