[x1,x2,x3,x4,x5,x6]=ndgrid(0:1);
x1 = x1(:);
x2 = x2(:);
x3 = x3(:);
x4 = x4(:);
x5 = x5(:);
x6 = x6(:);
b = [x1+x2+x3+(x4+1).*(x5+x6+1)-x1.*x2, ...
x2+x3+x4+(x5+1).*(x6+x1+1)-x2.*x3, ...
x3+x4+x5+(x6+1).*(x1+x2+1)-x3.*x4, ...
x4+x5+x6+(x1+1).*(x2+x3+1)-x4.*x5, ...
x5+x6+x1+(x2+1).*(x3+x4+1)-x5.*x6, ...
x6+x1+x2+(x3+1).*(x4+x5+1)-x6.*x1 ];
b=mod(b,2);
idx = find(all(b==0,2));
for i=1:length(idx)
k=idx(i);
fprintf('x1=%d,x2=%d,x3=%d,x4=%d,x5=%d,x6=%d\n', x1(k), x2(k), x3(k), x4(k), x5(k), x6(k));
end
x1=1,x2=0,x3=0,x4=0,x5=0,x6=0
x1=0,x2=1,x3=0,x4=0,x5=0,x6=0
x1=0,x2=0,x3=1,x4=0,x5=0,x6=0
x1=0,x2=0,x3=0,x4=1,x5=0,x6=0
x1=0,x2=0,x3=0,x4=0,x5=1,x6=0
x1=0,x2=0,x3=0,x4=0,x5=0,x6=1
x1=1,x2=1,x3=1,x4=1,x5=1,x6=1