Remark on an equivalent relation in least square approximation

In this note it is shown that the least square inverse of the 2-D polynomial B(z1, z2) = b00+ bmtz1^mz2^t+ bnsz1ⁿz2^s+ bm+n, s+tċ z1^m+nz2^s+twith (nt - ms) ≠ 0 is stable. This extends the Shanks´ conjecture for a larger class of 2-D polynomials.