Intl. Trans. in Op. Res. 00 (2015) 1–41 DOI: 10.1111/itor.12199 INTERNATIONAL TRANSACTIONS IN OPERATIONAL RESEARCH A research survey: review of flexible job shop scheduling techniques Imran Ali Chaudhry a and Abid Ali Khan b a Department of Industrial Engineering, National University of Sciences & Technology (NUST), Islamabad, Pakistan b Department of Aeronautics and Astronautics, Institute of Space Technology (IST), Islamabad, Pakistan E-mail: imran_chaudhry@yahoo.com [Chaudhry]; khanabid62@hotmail.com [Khan] Received 16 October 2014; received in revised form 7 May 2015; accepted 9 July 2015 Abstract In the last 25 years, extensive research has been carried out addressing the flexible job shop scheduling (JSS) problem. A variety of techniques ranging from exact methods to hybrid techniques have been used in this research. The paper aims at presenting the development of flexible JSS and a consolidated survey of various techniques that have been employed since 1990 for problem resolution. The paper comprises evaluation of publications and research methods used in various research papers. Finally, conclusions are drawn based on performed survey results. Keywords: scheduling; flexible job shop; partial flexibility; total flexibility; heuristics; metaheuristics 1. Introduction The last three decades have seen extensive development of efficient techniques to solve the flex- ible job shop scheduling problem (FJSSP). The scope and purpose of this paper is to present a survey of various techniques used for solving FJSSP using different objective functions. Nu- merous approaches have thus been investigated and these techniques are classified for ease of analysis. The paper comprises the following major sections. The FJSSP is defined in Section 2. A summary of sources for the published papers and their year-wise distribution is presented in Section 3 and later a summary of various objective functions is given in Section 4. Section 5 gives a brief description of each technique used along with salient features of published work. Analysis and discussion of the survey results are presented in Section 6 and the paper concludes with a future research roadmap. C  2015 The Authors. International Transactions in Operational Research C  2015 International Federation of Operational Research Societies Published by John Wiley & Sons Ltd, 9600 Garsington Road, Oxford OX4 2DQ, UK and 350 Main St, Malden, MA02148, USA.