@misc{Marinov_Evgeniy_Modern_2014, author={Marinov, Evgeniy}, copyright={Creative Commons Attribution BY 4.0 license}, address={Warszawa}, journal={Książka = Book}, howpublished={online}, year={2014}, publisher={Instytut Badań Systemowych. Polska Akademia Nauk}, publisher={Systems Research Institute. Polish Academy of Sciences}, language={eng}, abstract={Every quasi-ordered set (Y,≤) can be naturally split into equivalence classes and its factorization by that equivalence relation turned into partially ordered set as described by Birkhoff [3]. “Necessity” and “possibility” operators (denoted □ and ◊ respectively) for intuitionistic fuzzy sets have been introduced by Atanassov. We investigate them in more detail describing the structure of the classes from the corresponding equivalent relations on IFS(X) derived from the modal quasi-orderings. Some new statements about modal operators are introduced and we put light on them from various points of view.}, title={Modern approaches in fuzzy sets, intuitionistic fuzzy sets, generalized nets and related topics. Volume I: Foundations * On modal operators and quasi-orderings for IFSs}, type={Text}, URL={http://rcin.org.pl/Content/198434/PDF/KS-2014-02-T1P08.pdf}, }