The pseudo-effective pushforward conjecture for cohomology classes

Let XX and YY be smooth complex projective varieties and let φ:XY\varphi:X\rightarrow Y be a morphism. For a smooth variety, pushforward in cohomology is the Gysin morphism obtained using Poincare duality. A subvariety of codimension ll is contracted by φ\varphi exactly when its cohomology class is annihilated by this morphism.

Cohomological pseudo-effective pushforward conjecture. Any pseudo-effective class αH2l(X,R)\alpha\in H^{2l}(X,\mathbf{R}) such that φα=0\varphi_*\alpha=0 belongs to the real vector space, respectively the closed convex cone, spanned by classes of ll-codimensional subvarieties of XX contracted by φ\varphi.

This is the cohomological formulation of the preceding conjecture under Poincare duality. The source presents it as a conjectural extension of the established relationship for algebraic subvarieties; the general assertion remains open.

Sources & referencesView supporting material

Primary source

O. Debarre, Z. Jiang and C. Voisin, “Pseudo-effective classes and pushforwards”, arXiv:1301.4002 (2013).

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