sentences:  An outcome of that meeting was a new list of mathematical problems, the first of which, due to Manin (1976, p. 36), questioned whether classical set theory was an adequate paradigm for treating collections of indistinguishable elementary particles in quantum mechanics.He suggested that such collections cannot be sets in the usual sense, and that the study of such collections required a "new language".The use of the term "quasi-set" follows a suggestion in da Costa's 1980 monograph "Ensaio sobre os Fundamentos da Lógica" (see da Costa and Krause 1994), in which he explored possible semantics for what he called "Schrödinger Logics".