I have read the papers about EULER, velvet and soapdenovo, but I am still confused about how to choose the K values. It is a common practice to test several K values and choose the best one among them according to the results. But I think there may be some clues indicating the proper range of K and the K values should not be tested blindly. For example, obviously the K should be less than the maximal length of the reads. Is there a way to estimate roughtly the proper range of K values according to the genome size, sequenceing depth, reads length or something else? How do you choose the K value? Many thanks.