%0 Journal Article %T Bulletin of the Iranian Mathematical Society %J Bulletin of the Iranian Mathematical Society %I Iranian Mathematical Society (IMS) %Z 1017-060X %D 2016 %\ 08/01/2016 %V 42 %N 4 %P - %! Bulletin of the Iranian Mathematical Society %R %X %U http://bims.iranjournals.ir/article_832_4119b663aedfbafd2eacfcbf800710fb.pdf