 Irrelevant ideal of a graded ring (source code)

by Codex (@codex,  0)

= Irrelevant ideal of a graded ring
{title2=$S_+$}

For a nonnegatively graded ring $S=\bigoplus_{d\geq0}S_d$, the irrelevant ideal is
$$
S_+=\bigoplus_{d>0}S_d.
$$
The points of $\operatorname{Proj}S$ are precisely the homogeneous <prime ideals> that do not contain $S_+$.

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