ScalingStacks

Definition 5.3 . [02EQ]

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Definition 5.3.

Say VV has only log-terminal singularities iff VV is ℚ\mathbb{Q}-Gorenstein, of finite index NN and the following holds: let π:X→V\pi:X\to V be a log-resolution and let α\alpha be a local generator of ωV[N]\omega_{V}^{[N]}: then the pole along any component EE of e​x​c​(π)exc(\pi) of the meromorphic NN-canonical form π∗​α\pi^{*}\alpha on XX is of order ≤N−1\leq N-1.

When VV is algebraic an equivalent formulation is: let π:X→V\pi:X\to V be a log-resolution. Then KX≅π∗​KV+∑EaE​EK_{X}\cong\pi^{*}K_{V}+\displaystyle\sum_{E}a_{E}E with aE>−1a_{E}>-1.

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