Skip to content

Fixing small bug in ToricHigherDirectImages #3757

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Apr 30, 2025
Merged

Fixing small bug in ToricHigherDirectImages #3757

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
21 changes: 19 additions & 2 deletions M2/Macaulay2/packages/ToricHigherDirectImages.m2
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -494,7 +494,7 @@ HDI (ToricMap, ZZ, Module) := Module => (phi, i, D) -> (
if not isFreeModule D then error("-- module is not free");
if rank D != 1 then error("-- module is not rank one");
-- this chooses a divisor to represent the twist.
inp := flatten entries( (inverse fromCDivToPic source phi) * transpose matrix degrees D );
inp := -flatten entries( (inverse fromCDivToPic source phi) * transpose matrix degrees D );
HDI(phi, i, inp)
)
HDI (ToricMap, ZZ, CoherentSheaf) := Module => (phi, i, D) -> sheaf(target phi, HDI(phi, i, module D))
Expand Down Expand Up @@ -919,7 +919,7 @@ doc ///
phi = map(Z, X, matrix {{0,-1},{1,0}});
M = (ring X)^{{-6,3}};
RM = prune phi_*^0 M
L = OO_X(6,-3);
L = sheaf_X M;
RL = prune phi_*^1 L
annihilator RL
SeeAlso
Expand Down Expand Up @@ -1063,4 +1063,21 @@ HT = computeEigencharacters(phi,1,D);
assert(set keys HT == set {matrix{{0},{1}}, matrix{{0},{-1}}})
///

TEST ///
X = smoothFanoToricVariety(4,13);
f = (nefRayContractions X)_1;
Y = target f;
D = {-1,-1,-1,-1,-1,-1,-1};
D' = toricDivisor X
L = OO D'
assert(f_*^0 D == 0)
assert(f_*^1 D == 0)
assert(f_*^0 D == f_*^0 D')
assert(f_*^1 D == f_*^1 D')
assert(f_*^2 D == f_*^2 D')
assert(f_*^0 D == module f_*^0 L)
assert(f_*^1 D == module f_*^1 L)
assert(f_*^2 D == module f_*^2 L)
///

end--