A few more numbers for "the" big model @apturner @emikelsons :

• b_4(X_Sigma) = 815, X_Sigma the toric ambient space of the resolved model. So we have H^(2,2) \cong Q^815, and this would be our "naive" basis for G4-flux candidates.
• The newly introduced method in this PR identifies 629 basis elements of H^(2,2) which restrict - most likely - non-trivially to Y^4.

For details on what I mean by "most likely", see the changes in g4.md.

Calling the new method on the SU(5)xU(1) restricted Tate model leads to an error, the following code reproduces the error:
julia> B3 = projective_space(NormalToricVariety, 3)
Normal toric variety

julia> Kbar = anticanonical_divisor_class(B3)
Divisor class on a normal toric variety

julia> t = literature_model(arxiv_id = "1109.3454",
equation = "3.1", base_space = B3, defining_classes = Dict("w"=>Kbar));
Construction over concrete base may lead to singularity enhancement. Consider computing singular_loci. However, this may take time!

julia> ambient_space_models_of_g4_fluxes(t, check = false);

I think the problem lies on line 137 of the basis_of_h22 code, where an error occurs, if remaining_relations are empty

Calling the new method on the SU(5)xU(1) restricted Tate model leads to an error, the following code reproduces the error: julia> B3 = projective_space(NormalToricVariety, 3) Normal toric variety

julia> Kbar = anticanonical_divisor_class(B3) Divisor class on a normal toric variety

julia> t = literature_model(arxiv_id = "1109.3454", equation = "3.1", base_space = B3, defining_classes = Dict("w"=>Kbar)); Construction over concrete base may lead to singularity enhancement. Consider computing singular_loci. However, this may take time!

julia> ambient_space_models_of_g4_fluxes(t, check = false);

Good catch. Thank you!

I think the problem lies on line 137 of the basis_of_h22 code, where an error occurs, if remaining_relations are empty

Indeed, I did not catch the case for which there are no remaining relations. 9e586c0 should fix this.

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.47%. Comparing base (2814275) to head (ed02e4e).
Report is 3 commits behind head on master.

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+ Misses      13261    13259    -2