Adam Grygiel  
                                   (2008)   
                
                
                    Bulletin of the Polish Academy of Sciences. Mathematics
                
                
                        
                            
            Let K be a field and let L = K[ξ] be a finite field extension of K of degree m > 1. If f ∈ L[Z] is a polynomial, then there exist unique polynomials  such that . A. Nowicki and S. Spodzieja proved that, if K is a field of characteristic zero and f ≠ 0, then  have no common divisor in  of positive degree. We extend this result to the case when L is a separable extension of a field K of arbitrary characteristic. We also show that the same is true for a formal power series in several...