ISSN : 1226-0657
D. Dubois and H. Prade introduced the notions of fuzzy numbers and defined its basic operations [3]. R. Goetschel, W. Voxman, A. Kaufmann, M. Gupta and G. Zhang [4,5,6,9] have done much work about fuzzy numbers. Let <TEX>$\mathbb{R}$</TEX> the set of all real numbers and <TEX>$F^{*}(\mathbb{R})$</TEX> all fuzzy subsets defined on <TEX>$\mathbb{R}$</TEX>. G. Zhang [8] defined the fuzzy number <TEX>$\tilde{a}\;\in\;F^{*}(\mathbb{R})$</TEX> as follows : (omitted)