“…This assumption has been discussed very often in the k-means literature (see, for instance, [2]). Some results are known in the case that E = IR and α = 0 (see, for instance, [13], [8], [5], [14], and [9]), but, at our best acknowledge, yet there is no satisfactory result even in the case E = IR 2 , k = 2 and α = 0.…”