## On Gorenstein surface singularities with fundamental genus $$p_ f\geq 2$$ which satisfy some minimality conditions.(English)Zbl 0848.14017

In this paper we study normal surface singularities whose fundamental genus (:= the arithmetic genus $$p_a (Z)$$ of the fundamental cycle $$Z)$$ is equal or greater than 2. For those singularities, we define some minimality conditions which are similar to Laufer’s conditions for elliptic singularities, and we study the relation between them under the condition to be Gorenstein. Especially, we prove that
“If $$\pi : (\widetilde X,A) \to (X,x)$$ is a resolution of a Gorenstein surface singularity with $$p_g (X,x) \geq 1$$ and $$K = Z + E$$, then $$p_g (X,x) = p_a (Z) + 1$$, where $$K$$ and $$E$$ are the canonical cycle and minimal cycle, respectively”.
Further we define some sequence of such singularities, which is analogous to elliptic sequence in the sense of Yau. In the case of hypersurface singularities of Brieskorn type, we study some properties of the sequences.

### MSC:

 14J17 Singularities of surfaces or higher-dimensional varieties 14J70 Hypersurfaces and algebraic geometry 14E15 Global theory and resolution of singularities (algebro-geometric aspects)
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