def s_poly(cp):
 return lbp_sub(lbp_mul_term(cp[2], cp[1]), lbp_mul_term(cp[5], cp[4]))

def s_poly ( cp ) : return lbp_sub ( lbp_mul_term ( cp [ 2 ] , cp [ 1 ] ) , lbp_mul_term ( cp [ 5 ] , cp [ 4 ] ) )
compute the s-polynomial of a critical pair .