1. In his speech recorded in Rev. Mod. Physics, 32,175 (1962) and in private conversation, Charles Coulson insisted on the importance of the 2-matrix as the encoder of correlation and on the desirability of finding ways to work directly with it instead of with the wavefunction which contains much redundant information. Because of this, in 1971 he invited Coleman to give 12 lectures about RDM’s to his Seminar in Oxford. Coulson sat in the front row participating actively in discussion.
2. The correlation matrix was defined by Coleman on p. 6 of the J. of Low Temp. Physics, 74, 1-17(1989). This idea was made more precise in papers by Coleman and Yukalov: See Nuovo Cimento B108,1377 (1993);
3. Int.J. of Modern Physics, B 25, 3503-3515 (1996) and references therein.
4. Zhislin G.M., Trudi Mosk. Mat. Obsc, 9, 81 (1960), Theorem III, p.84
5. Hill R.N., J. Math Physics, 18, 2316 (1977)