If $D$ is a domain and $K$ is field then for $x\in K$, $xD$ is a fractional ideals of $D$. If $xD$ and $yD$ are two fractional ideals then is true or not $xyD\subseteq xD$ ?. Thanks
fractional ideals
2
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abstract-algebra
commutative-algebra
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4What about $D = \mathbf Z$, $x = 2$, $y = 1/2$? – 2012-03-29