文摘
One of the most frequently referenced monographs on power series rings, “Power Series over Commutative Rings” by James W. Brewer, states in Theorem 21 that if M is a non-SFT maximal ideal of a commutative ring R with identity, then there exists an infinite ascending chain of prime ideals in the power series ring 916300573&_mathId=si1.gif&_user=111111111&_pii=S0022404916300573&_rdoc=1&_issn=00224049&md5=747592f49fafc69ba050646c45e341f4" title="Click to view the MathML source">R〚X〛, 916300573&_mathId=si19.gif&_user=111111111&_pii=S0022404916300573&_rdoc=1&_issn=00224049&md5=deae601c6b157957629b804a1063e4f7" title="Click to view the MathML source">Q0⊊Q1⊊⋯⊊Qn⊊⋯ such that 916300573&_mathId=si3.gif&_user=111111111&_pii=S0022404916300573&_rdoc=1&_issn=00224049&md5=c4d9fd1f98c614973fb6fcf092d3aa78" title="Click to view the MathML source">Qn∩R=M for each n . Moreover, the height of 916300573&_mathId=si4.gif&_user=111111111&_pii=S0022404916300573&_rdoc=1&_issn=00224049&md5=ca404f765ab8fd5db7afe94c878f0369" title="Click to view the MathML source">M〚X〛 is infinite. In this paper, we show that the above theorem is false by presenting two counter examples. The first counter example shows that the height of 916300573&_mathId=si4.gif&_user=111111111&_pii=S0022404916300573&_rdoc=1&_issn=00224049&md5=ca404f765ab8fd5db7afe94c878f0369" title="Click to view the MathML source">M〚X〛 can be zero (and hence there is no chain 916300573&_mathId=si19.gif&_user=111111111&_pii=S0022404916300573&_rdoc=1&_issn=00224049&md5=deae601c6b157957629b804a1063e4f7" title="Click to view the MathML source">Q0⊊Q1⊊⋯⊊Qn⊊⋯ of prime ideals in 916300573&_mathId=si1.gif&_user=111111111&_pii=S0022404916300573&_rdoc=1&_issn=00224049&md5=747592f49fafc69ba050646c45e341f4" title="Click to view the MathML source">R〚X〛 satisfying 916300573&_mathId=si3.gif&_user=111111111&_pii=S0022404916300573&_rdoc=1&_issn=00224049&md5=c4d9fd1f98c614973fb6fcf092d3aa78" title="Click to view the MathML source">Qn∩R=M for each n). In this example, the ring R is one-dimensional. In the second counter example, we prove that even if the height of 916300573&_mathId=si4.gif&_user=111111111&_pii=S0022404916300573&_rdoc=1&_issn=00224049&md5=ca404f765ab8fd5db7afe94c878f0369" title="Click to view the MathML source">M〚X〛 is uncountably infinite, there may be no infinite chain 916300573&_mathId=si6.gif&_user=111111111&_pii=S0022404916300573&_rdoc=1&_issn=00224049&md5=867a7c74938c2da292f5f07b0fcb414c" title="Click to view the MathML source">{Qn} of prime ideals in 916300573&_mathId=si1.gif&_user=111111111&_pii=S0022404916300573&_rdoc=1&_issn=00224049&md5=747592f49fafc69ba050646c45e341f4" title="Click to view the MathML source">R〚X〛 satisfying 916300573&_mathId=si3.gif&_user=111111111&_pii=S0022404916300573&_rdoc=1&_issn=00224049&md5=c4d9fd1f98c614973fb6fcf092d3aa78" title="Click to view the MathML source">Qn∩R=M for each n.