Necessary and sufficient conditions for some two

0 downloads 0 Views 195KB Size Report
b b -a -o - b -a -o b 0 a -6 -6 a b 0 - 0. - - b. -a b. 0 b b 0 a 0. a a - b b b b - 6. 0 0. O a - 0 - 0 0 а - - а – ъ о. a a 6 -6 -6 bb bb. -a a a a - a b b a -b 6 -6 -6 b b 0 0 a 0 ...