“…We prove the second result by deriving another linear ordering G (k, n) of the P PEs in which consecutive PEs are (D) distance apart by swapping suitable pairs of PEs in G(k, n). For example, G(6, 2) = 00, 01, 02, 03, 04, 05, 15,14,13,12,11,10,20,21,22,23,24,25,35,34,33,32,31,30,40,41,42,43,44,45, 55, 54, 53, 52, 51, 50 and G(5, 2) = 00, 01, 02, 03, 04, 14,13,12,11,10,20,21,22,23,24,34,33,32,31,30,40,41,42,43,44 , where "swappable" PEs-to be defined shortly-are underlined and PEs at odd-numbered positions that are not swappable are overlined. Note that when k is even, P is even, when k is odd, P is odd, and that there are an even number of PEs at odd-numbered positions (i.e., p i such that i is odd), regardless of whether k is even or odd.…”