Suppose $f: A \rightarrow B$ is a local homomorphism of local rings. Assume that $A$ and $B$ are noetherian, regular and $\mathrm{Spec} B \rightarrow \mathrm{Spec} A$ is quasi-finite. Is is necessary that $f$ is flat?
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5$\begingroup$ Obviously not. But this looks like homework, and anyways is not appropriate for mathoverflow. Try math.stackexchange.com instead? Or consider a closed immersion. $\endgroup$– Will SawinJun 4, 2012 at 0:09
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$\begingroup$ You need a dimension condition to hold. $\endgroup$– Mahdi Majidi-ZolbaninJun 4, 2012 at 5:51
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