
In the paper under review the author proves that the existence of generic polynomials and generic extensions [in the sense of \textit{D. J. Saltman}, Adv. Math. 43, 250-283 (1982; Zbl 0484.12004)] are equivalent over an infinite field. Here one calls a monic polynomial \(P(s_1,\dots,s_m;X) \in K(s_1,\dots,s_m)[X]\), where \(s_1,\dots,s_m\) are indeterminates over the field \(K\), generic for a group \(G\) if (i) the splitting field of \(P(s_1,\dots,s_m;X)\) over \(K(s_1,\dots,s_m)\) is a \(G\)-extension, i.e. a Galois extension of \(K(s_1,\dots,s_m)\) with Galois group isomorphic to \(G\), and (ii) every \(G\)-extension of a field \(L\) containing \(K\) is the splitting field (over \(L\)) of a polynomial \(P(a_1,\dots,a_m;X)\) for some \(a_1,\dots,a_m \in L.\) Using \textit{F. R. DeMeyer}'s result [J. Algebra 84, 441-448 (1983; Zbl 0521.12014)] one gets that the existence of a generic polynomial \(P\) with finite group \(G\) is equivalent to the existence of a generic polynomial \(P'\) with the stronger property that every Galois extension \(N/L\) with \(\text{Gal}(N/L) \leq G\) appears as the splitting field of a specialization of \(P'.\) Note that meanwhile \textit{G. Kemper} obtained an even stronger result (to appear in Manuscr. Math.): If a polynomial \(P\) is generic for a finite group \(G\) over an infinite field \(K,\) then every Galois extension \(N/L\) with \(K \subseteq L\) and \(\text{Gal}(N/L) \leq G\) appears as the splitting field of a specialization of \(P.\)
Computational Mathematics, Algebra and Number Theory, generic polynomials, Separable extensions, Galois theory, generic extensions
Computational Mathematics, Algebra and Number Theory, generic polynomials, Separable extensions, Galois theory, generic extensions
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