For small values of n it is easily seen that the components of a bigraph on 2n points are themselves bigraphs of their point set.Simmons had asked whether this was always the case and had shown that if a bigraph on 2n points existed which had a component that was not in itself a bigraph then 2n≧16. In this paper we answer his question affirmatively by using a result ofLovász. We also show that any two components of a bigraph intersect.
Authors:A. H. Mohagheghi, S. T. Shanks, J. A. Zigmond, G. L. Simmons and S. L. A. Ward
The results of radioecological investigations in the Syrdarya river basin in the Republic of Kazakhstan are presented. The work was carried out under the International Navruz Project. Nuclear activation analysis, X-ray fluorescence, and &-spectrometry were used to measure the element and radionuclide (137Cs, 40K and 238U, 235U, and 232 Th families) compositions of soil, water, bottom sediments and vegetation. Samples were collected at 15 control points in Kazakhstan along the Syrdarya river and its inflows during four expeditions (autumn 2000 and 2001, spring 2001 and 2002).