Two examples of surfaces with normal crossing singularities

作者：Kollar Janos^*

来源：Science China Mathematics, 2011, 54(8): 1707-1712.

DOI：10.1007/s11425-010-4161-x

• singular surface
• canonical ring
• ampleness criteria

This note gives two examples of surfaces with normal crossing singularities. In the first example the canonical ring is not finitely generated. In the second, the canonical line bundle is not ample but its pull back to the normalization is ample. The latter answers in the negative a problem left unresolved in III.2.6.2 of A parts per thousand l,ments de g,ometrie alg,brique, 1961, and raised again by Viehweg.

• 出版日期2011-8