Very general monomial valuations of P2 and a Nagata type conjecture

被引:6
|
作者
Dumnicki, Marcin [1 ]
Harbourne, Brian [2 ]
Kueronya, Alex [3 ]
Roe, Joaquim [4 ]
Szemberg, Tomasz [5 ]
机构
[1] Jagiellonian Univ, Dept Math, PL-30348 Krakow, Poland
[2] Univ Nebraska, Dept Math, Lincoln, NE 68588 USA
[3] Goethe Univ Frankfurt, Inst Math FB12, Robert Mayer Str 6-8, D-60325 Frankfurt, Germany
[4] Univ Autonoma Barcelona, Dept Matemat, Fac Ciencies, C1-346, Bellaterra 08193, Barcelona, Spain
[5] Pedag Univ Cracow, Dept Math, Podchorazych 2, PL-30084 Krakow, Poland
关键词
Nagata Conjecture; SHGH Conjecture; Seshadri constants; monomial valuations; anticanonical divisor; RATIONAL SURFACES; DIMENSIONS; DIVISORS; CURVES; IDEALS;
D O I
10.4310/CAG.2017.v25.n1.a4
中图分类号
O1 [数学];
学科分类号
0701 ; 070101 ;
摘要
It is well known that multi-point Seshadri constants for a small number t of points in the projective plane are submaximal. It is predicted by the Nagata conjecture that their values are maximal for t >= 9 points. Tackling the problem in the language of valuations one can make sense of t points for any real t >= 1. We show somewhat surprisingly that a Nagata-type conjecture should be valid for t >= 8 + 1/36 points and we compute explicitly all Seshadri constants (expressed here as the asymptotic maximal vanishing element) for t >= 7 + 1/9. In the range 7 + 1/9 <= t <= 8 + 1/36 we are able to compute some sporadic values.
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页码:125 / 161
页数:37
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