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nefRayContractions -- produces all contractions corresponding to rays in the nef cone

Description

This method is a convenient way to produce all of the nef contractions corresponding to the rays of the nef cone, without the user needing to know those rays.

i1 : X = hirzebruchSurface 1;
i2 : L = nefRayContractions X

o2 = {| 1 0 |, | 1 0 |}
               | 0 1 |

o2 : List
i3 : assert(isProjective target L_0 and dim target L_0 == 1);
i4 : assert(isProjective target L_1 and dim target L_1 == 2);
i5 : assert(rank picardGroup target L_1 == 1);

See also

Ways to use nefRayContractions:

  • nefRayContractions(NormalToricVariety)

For the programmer

The object nefRayContractions is a method function.


The source of this document is in /build/reproducible-path/macaulay2-1.25.05+ds/M2/Macaulay2/packages/ToricHigherDirectImages.m2:790:0.