International Journal of Pure and Applied Mathematics Volume 118 No. 1 2018, 1-7 ISSN: 1311-8080 (printed version); ISSN: 1314-3395 (on-line version) url: http://www.ijpam.eu doi: 10.12732/ijpam.v118i1.1 P A ijpam.eu COSINE SIMILARITY MEASURE FOR ROUGH INTUITIONISTIC FUZZY SETS AND ITS APPLICATION IN MEDICAL DIAGNOSIS H. Jude Immaculate 1 § , I. Arockiarani 2 1 Department of Mathematics Karunya University Coimbatore, INDIA 2 Department of Mathematics Nirmala College for Women Coimbatore, INDIA Abstract: Similarity measure is an important mathematical tool used in medical diagnosis, pattern recognition etc. In this paper a cosine similarity for rough intuitionistic fuzzy set is proposed. Also we apply the notion of weighted rough intuitionistic fuzzy approach to cosine similarity measure for further investigation. Finally a medical diagnosis problem is defined to verify the proposed similarity measure. AMS Subject Classification: 03E72, 04A72, 28E10, 26E50, 94D05 Key Words: rough intuitionistic fuzzy sets, cosine similarity measure, intuitionistic fuzzy sets, rough sets 1. Introduction Similarity measure is an imperative topic in fuzzy set theory. It is a vital tool for determining the degree of similarity between two objects. It has been rigorously Received: September 7, 2015 Revised: November 18, 2017 Published: February 14, 2018 c  2018 Academic Publications, Ltd. url: www.acadpubl.eu § Correspondence author