Fix minor triangulation bug

experimental/FTheoryTools/test/runtests.jl

@@ -1,5 +1,5 @@
 using Test
 using Oscar
-#= set_verbosity_level(:FTheoryConstructorInformation, -1)
+set_verbosity_level(:FTheoryConstructorInformation, -1)
 include("weierstrass.jl")
-include("tate.jl") =#
+include("tate.jl")

src/AlgebraicGeometry/ToricVarieties/NormalToricVarieties/standard_constructions.jl

@@ -616,19 +616,15 @@ function normal_toric_variety_from_glsm(charges::ZZMatrix; set_attributes::Bool
   map = hom(G1, G2, transpose(charges))
   ker = kernel(map)
   embedding = snf(ker[1])[2] * ker[2]
-  rays = transpose(embedding.map)
+  integral_rays = transpose(embedding.map)
 
   # identify the points to be triangulated
-  pts = zeros(ZZ, nrows(rays), ncols(charges)-nrows(charges))
-  for i in 1:nrows(rays)
-    pts[i, :] = [ZZRingElem(c) for c in rays[i, :]]
-  end
-  zero = [0 for i in 1:ncols(charges)-nrows(charges)]
-  pts = vcat(matrix(ZZ, transpose(zero)), matrix(ZZ, pts))
+  pts = matrix(ZZ, zeros(nrows(integral_rays)+1, ncols(integral_rays)))
+  pts[2:end, :] = integral_rays
 
   # construct varieties
-  integral_rays = vcat([pts[k,:] for k in 2:nrows(pts)])
-  max_cones = IncidenceMatrix([[c[i]-1 for i in 2:length(c)] for c in _find_full_star_triangulation(pts)])
+  triang = _find_full_star_triangulation(pts)
+  max_cones = IncidenceMatrix([[c[i]-1 for i in 2:length(c)] for c in triang])
   variety = normal_toric_variety(integral_rays, max_cones; non_redundant = true)
 
   # set the attributes and return the variety

src/PolyhedralGeometry/triangulations.jl

@@ -72,18 +72,21 @@ function _is_full_triangulation(sop::SubdivisionOfPoints{QQFieldElem})
   return true
 end
 
+_is_star_triangulation(sop::SubdivisionOfPoints{QQFieldElem}) = all(cell -> 1 in cell, maximal_cells(sop))
 
 
-function _find_full_star_triangulation(pts::ZZMatrix)
+
+function _find_full_star_triangulation(pts::ZZMatrix; seed::Int=-1)
+  seed == -1 || Random.seed!(seed)
   n = nrows(pts)
   wts = rand(0:100000, n)
   # Weight of first points is lowest
-  wts[1] = -1
+  wts[1] = -1000000
   sop = subdivision_of_points(pts, wts)
-  while !_is_full_triangulation(sop)
-     wts = rand(0:100000, n)
-     wts[1] = -1
-     sop = subdivision_of_points(pts, wts)
+  while !(_is_full_triangulation(sop) && _is_star_triangulation(sop))
+    wts = rand(0:100000, n)
+    wts[1] = -1000000
+    sop = subdivision_of_points(pts, wts)
   end
   return collect(maximal_cells(sop))
 end

test/PolyhedralGeometry/runtests.jl

@@ -16,3 +16,4 @@ include("timing.jl")
 include("solve_integrally.jl")
 include("lineality.jl")
 include("scalar_types.jl")
+include("triangulations.jl")

test/PolyhedralGeometry/triangulations.jl

@@ -0,0 +1,18 @@
+@testset "Triangulations" begin
+  @testset "FTheory" begin
+    pts = matrix(ZZ, [0 0 0 0; -3 -4 -8 2; 0 0 1 -1; 1 0 0 0; 0 1 0 0; 0 0 1 0; 0 0 0 1])
+    triang = Oscar._find_full_star_triangulation(pts; seed=994)
+    sop = subdivision_of_points(pts, triang)
+    @test Oscar._is_full_triangulation(sop)
+    @test Oscar._is_star_triangulation(sop)
+  end
+
+  @testset "Square" begin
+    pts = matrix(ZZ,[0 0; 1000 0; 0 1000; 501 501])
+    pts = 1000000000*pts
+    triang = Oscar._find_full_star_triangulation(pts; seed=47235)
+    sop = subdivision_of_points(pts, triang)
+    @test Oscar._is_full_triangulation(sop)
+    @test Oscar._is_star_triangulation(sop)
+  end
+end