Mathematical Research Letters

Volume 11 (2004)

Number 6

Even sets of four nodes on rational surfaces

Pages: 799 – 808

DOI: http://dx.doi.org/10.4310/MRL.2004.v11.n6.a7

Authors

Alberto Calabri (Università degli Studi di Bologna)

Ciro Ciliberto (Università degli Studi di Roma “Tor Vergata”)

Margarida Mendes Lopes (Instituto Superior Técnico)

Abstract

We describe smooth rational projective algebraic surfaces $X$, over an algebraically closed field of characteristic different from $2$, having an even set of four disjoint $(-2)$-curves $N_1,\ldots,N_4$, i.e. such that $N_1+\cdots+N_4$ is divisible by 2 in $\Pic(X)$.

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