%0 Journal Article %A Tardif, Claude %T The chromatic number of the product of two graphs is at least half the minimum of the fractional chromatic numbers of the factors %J Commentationes Mathematicae Universitatis Carolinae %D 2001 %P 353-355 %V 42 %N 2 %I mathdoc %U http://geodesic.mathdoc.fr/item/CMUC_2001__42_2_a11/ %G en %F CMUC_2001__42_2_a11