en و موضوعات مربوط Other Related Subject پژوهشي Research <p> <i> In order to have better insight of project characteristics, different kinds of fuzzy analysis for project networks have been recently proposed, most of which consider activities duration as the main and only source of imprecision and vagueness, but as it is usually experienced in real projects, the structure of the network is also subject to changes. In this paper we consider three types of imprecision namely activity duration, activity existence and precedence relation existence which make our general fuzzy project network. Subsequently, a corrected forward recursion is proposed for analysis of this network. Since the convexity and normalization of traditional fuzzy numbers are not satisfied, some corrected algebraic operations are also presented. Employing the proposed method for a real project reveals that our method results in more applicable and realistic times for activities and project makespan in comparison to </i></p><i>Classic fuzzy PERT. </i> Project network, Fuzzy PERT,Fuzzy struc-ture,Non-convex fuzzy numbers,High-risk projects 73 82 http://ijiepr.iust.ac.ir/browse.php?a_code=A-10-203-1&slc_lang=en&sid=1 Reza Morovatdar morovatdar@dena.kntu.ac.ir 180031947532846002165 180031947532846002165 No PhD student at the Department of Industrial Engineering, K.N.Toosi University of Technology, Tehran, Iran Abdolah Aghaie aaghaie@kntu.ac.ir 180031947532846002166 180031947532846002166 Yes is Associate Professor at the Department of Industrial Engineering, K.N.Toosi University of Technology, Tehran, Iran Simak Haji Yakhchali 180031947532846002167 180031947532846002167 No Assistant Professor at the Department of Industrial Engineering, College of Engineering, University of Tehran, Tehran, Iran