// Workers AI · dad joke modeIs the Catanese surface tense? Because it's always stressed.

In mathematics, a Catanese surface is one of the surfaces of general type introduced by Fabrizio Catanese (1981).

Construction

The construction starts with a quintic V with 20 double points. Let W be the surface obtained by blowing up the 20 double points. Suppose that W has a double cover X branched over the 20 exceptional −2-curves. Let Y be obtained from X by blowing down the 20 −1-curves in X. If there is a group of order 5 acting freely on all these surfaces, then the quotient Z of Y by this group of order 5 is a Catanese surface. Catanese found a 4-dimensional family of curves constructed like this.

Invariants

The Catanese surface is a numerical Campedelli surface and hence has Hodge diamond

		1
	0		0
0		8		0
	0		0
		1

and canonical degree $K^{2}=2$. The fundamental group of the Catanese surface is $\mathbf {Z} /5\mathbf {Z}$, as can be seen from its quotient construction.

References

• Barth, Wolf P.; Hulek, Klaus; Peters, Chris A.M.; Van de Ven, Antonius (2004), Compact Complex Surfaces, Ergebnisse der Mathematik und ihrer Grenzgebiete. 3. Folge., vol. 4, Springer-Verlag, Berlin, ISBN 978-3-540-00832-3, MR 2030225
• Catanese, Fabrizio (1981), "Babbage's conjecture, contact of surfaces, symmetric determinantal varieties and applications", Inventiones Mathematicae, 63 (3): 433–465, doi:10.1007/BF01389064, ISSN 0020-9910, MR 0620679