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Lelong Number


A Lelong number measures the logarithmic singularity of a plurisubharmonic function, or the local concentration of an associated positive current. For a plurisubharmonic potential phi near x in C^n, the function convention is

 nu(phi,x)=liminf_(z->x)(phi(z))/(ln||z-x||).

Thus aln||z-x|| has Lelong number a for a>=0, while a locally bounded potential has Lelong number zero. Smooth changes of potential do not affect the number.

For the local weights of a semipositive singular Hermitian metric, zero Lelong numbers everywhere rule out logarithmic poles. They imply local integrability of e^(-tphi) for every fixed t>0.


See also

Plurisubharmonic Function, Singular Hermitian Metric

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References

Demailly, J.-P. Analytic Methods in Algebraic Geometry. Somerville, MA: International Press, 2012.

Cite this as:

Weisstein, Eric W. "Lelong Number." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/LelongNumber.html

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