Fix oscar-system#4018

joschmitt · Aug 21, 2024 · a24b598 · a24b598
1 parent 38cc0a9
commit a24b598
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Showing 3 changed files with 16 additions and 6 deletions.
diff --git a/src/Rings/mpoly-graded.jl b/src/Rings/mpoly-graded.jl
@@ -1503,6 +1503,7 @@ mutable struct HilbertData
     @req all(is_homogeneous, gens(I)) "The generators of the ideal must be homogeneous"
 
     G = groebner_assure(I)
+    singular_assure(I)
     cf = Singular.hilbert_series_data(G.S, W)
     return new(cf, W, I)
   end

diff --git a/src/Rings/mpoly-ideals.jl b/src/Rings/mpoly-ideals.jl
@@ -2069,7 +2069,7 @@ function grassmann_pluecker_ideal(subspace_dimension::Int, ambient_dimension::In
   o = degrevlex(base)
 
   return ideal(IdealGens(base,base.(gens(I)), o;
-                   keep_ordering=true,
+                   keep_ordering=false,
                    isReduced=true,
                    isGB=true))
 end
@@ -2112,12 +2112,12 @@ function grassmann_pluecker_ideal(ring::MPolyRing,
     return coeff_ring(numerator(c))
   end
   if !is_graded(ring)
-	 ring, _ = grade(ring)
+    ring, _ = grade(ring)
   end
   h = hom(base_ring(I), ring, coeffmap, gens(ring))
   converted_generators = elem_type(ring)[h(g) for g in groebner_basis(I; ordering = degrevlex(base_ring(I)))]
   ideal(IdealGens(ring, converted_generators, o;
-                   keep_ordering=true,
+                   keep_ordering=false,
                    isReduced=true,
                    isGB=true))
 end

diff --git a/test/Rings/mpoly.jl b/test/Rings/mpoly.jl
@@ -300,9 +300,18 @@ end
 end
 
 @testset "Grassmann Plücker Relations" begin
-    R, x = graded_polynomial_ring(residue_ring(ZZ, 7)[1], "x" => (1:2, 1:3))
-    test_ideal =ideal([x[1, 2]*x[2, 2] + 6*x[2, 1]*x[1, 3] + x[1, 1]*x[2, 3]])
-    @test grassmann_pluecker_ideal(R, 2, 4) == test_ideal
+  R, x = graded_polynomial_ring(residue_ring(ZZ, 7)[1], "x" => (1:2, 1:3))
+  test_ideal =ideal([x[1, 2]*x[2, 2] + 6*x[2, 1]*x[1, 3] + x[1, 1]*x[2, 3]])
+  @test grassmann_pluecker_ideal(R, 2, 4) == test_ideal
+
+  # Issue #4018
+  I = grassmann_pluecker_ideal(2, 5)
+  @test degree(I) == 5
+  @test dim(I) == 7
+  R, x = graded_polynomial_ring(GF(7), 10, "x")
+  I = grassmann_pluecker_ideal(R, 2, 5)
+  @test degree(I) == 5
+  @test dim(I) == 7
 end
 
 @testset "IdealGens" begin