3-fold

{{For2|the plants known as "threefold"|Trixis|the chess term|threefold repetition}}

In algebraic geometry, a 3-fold or threefold is a 3-dimensional algebraic variety.

The Mori program showed that 3-folds have minimal models.

References

{{Citation | last1=Matsuki | first1=Kenji | title=Introduction to the Mori program | publisher=Springer-Verlag | location=Berlin, New York | series=Universitext | isbn=978-0-387-98465-0 | mr=1875410 | year=2002}}
{{Citation | last1=Reid | first1=Miles | author1-link=Miles Reid | title=Journées de Géometrie Algébrique d'Angers, Juillet 1979/Algebraic Geometry, Angers, 1979 | publisher=Sijthoff & Noordhoff | location=Alphen aan den Rijn | mr=605348 | year=1980 | chapter=Canonical 3-folds | pages=273–310}}
{{Citation | last1=Roth | first1=L. | title=Algebraic threefolds, with special regard to problems of rationality | publisher=Springer-Verlag | location=Berlin, New York | series=Ergebnisse der Mathematik und ihrer Grenzgebiete (N.F.), Heft 6 | mr=0076426 | year=1955}}