Short Retraction Notice
The paper does not meet the standards of "Advances in Pure Mathematics".
This article has been retracted to straighten the academic record. In making this decision the Editorial Board follows COPE's Retraction Guidelines. The aim is to promote the circulation of scientific research by offering an ideal research publication platform with due consideration of internationally accepted standards on publication ethics. The Editorial Board would like to extend its sincere apologies for any inconvenience this retraction may have caused.
Editor guiding this retraction: Prof. Dexing Kong (EiC of APM)
The full retraction notice in PDF is preceding the original paper, which is marked "RETRACTED".
 Dubis, D. and Prade, H. (1980) Fuzzy Sets and Systems, Theory and Applications. Academic Press, New York.
 Zadeh, L.A. (1965) Fuzzy Sets. Information and Control, 8, 338-353.