One more counterexample in n-D systems-unimodular versus elementary operations

By a simple counterexample, it is shown that there are unimodular matrices which cannot be written as products of elementary matrices in the ring of n-D polynomials. As a consequence, some methods for the solution of n-D matrix polynomial equations published recently, which are based on the elementary operations in the ring of n-D polynomials, do not work.<
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