| Summary: | In the paper [14] Hochster gave a topological characterisation of those spaces X which arise as the prime spectrum of a commutative ring: they are the spectral spaces, defined as those topological spaces which are T_0, quasi-compact and sober, whose quasi-compact and open subsets form a basis for the topology and are closed under finite intersections. It is well known that the prime spectrum of a ring is always spectral; Hochster proved the converse by describing a construction which, starting from such a space X, builds a ring having the desired prime spectrum; however the construction given is (in Hochster's own words) very intricate, and has not been further exploited in the literature (a passing exception perhaps being the use of [14] Theorem 4 in the example on page 272 of [24]). In the finite setting, alternative constructions of a ring having a given spectrum are provided by Lewis [17] and Ershov [7], which, particularly in light of the work of Fontana in [8], appear to be more tractable, and at least more readily understood. This insight into the methods of constructing rings with a given spectrum is used to prove a result about which spaces may arise as the prime spectrum of a Noetherian ring: it is shown that every 1-dimensional Noetherian spectral space may be realised as the prime spectrum of a Noetherian ring. A close analysis of the two finite constructions considered here reveals considerable similarities between their underlying operation, despite their radically different presentations. Furthermore, we generalise the framework of Ershov's construction beyond the finite setting, finding that the ring we thus define on a space X contains the ring defined by Hochster's construction on X as a subring. We find that in certain examples these rings coincide, but that in general the containment is proper, and that the spectrum of the ring provided by our generalised construction is not necessarily homeomorphic to our original space. We then offer an additional condition on our ring which may (-and indeed in certain examples does) serve to repair this disparity. It is hoped that the analysis of the constructions presented herein, and the demonstration of the heretofore unrecognised connections between the disparate ring constructions proposed by various authors, will facilitate further investigation into the prime ideal structure of commutative rings.
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