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In this article, we introduce the fuzzy commutativity degree of  finite  fuzzy group G and some difinitions and concepts about it.
\begin{thebibliography}{99}



\bibitem{a10}
N. Ajmal and K.V. Thomas, A complete study of the lattices of fuzzy congruences and fuzzy normal subgroups,{\it Inform .Sci.},$~\bf{82}$(1995),197-218.

%خط زیر مشکل فاصله دارددر pdf
\bibitem{a8}
W. J .Liu, fuzzy-invariant subgroups and fuzzy ideals,\textit {Fuzzy sets and Systems.},$~\bf{21}$(1982),133-139.               


\bibitem{a13}
M. Taranauceanu, A note on the lattice of fuzzy  subgroups of a finite group,{\it J.of Mult.-Valued Logic & Soft Computing.},$~\bf{19}$(2012),537-545.



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