function [lower] = pop_yalmip(d)
sdpvar x y lower;
f = x^4*y^2 + x^2*y^4 -3*x^2*y^2 + 1;
g = [1-x;1+x;1-y;1+y];
[s1,c1] = polynomial([x y],2*d-2);
[s2,c2] = polynomial([x y],2*d-2);
[s3,c3] = polynomial([x y],2*d-2);
[s4,c4] = polynomial([x y],2*d-2);
F = [sos(f-lower-[s1 s2 s3 s4]*g), sos(s1), sos(s2), sos(s3), sos(s4)];
solvesos(F,-lower,[],[c1;c2;c3;c4;lower]);
double(lower)
end
