(string-grobner-system
"[-Y1^2-X1^2-2*A*X1+R1^2-A^2,-Y1^2-X1^2+2*A*X1+R2^2-A^2,R2+R1-2,-Y2^2-X2^2-2*A*X2+S1^2-A^2,-Y2^2-X2^2+2*A*X2+S2^2-A^2,S2+S1-2,X1*Y2+A*Y2-X2*Y1-A*Y1,R1*S1*U*V-S1*V-R1*V+1]"
'(X1 Y1 X2 Y2 R1 R2 S1 S2 V)
'(U A)
:cover '(("[-A^2*U+U-2]" "[A]"))
:main-order #'grevlex>
:parameter-order #'grevlex>
)