Randomized tests failing for `AlgClosure{fqPolyRepField}` #2691

lgoettgens · 2023-08-17T09:43:34Z

Starting with #2684, I noticed some seemingly random fails on the master CI with different julia versions.
All are pretty lengthy, but contain something like the following multiple times:

Basic functions: Error During Test at /home/runner/.julia/packages/AbstractAlgebra/lDlYU/test/Rings-conformance-tests.jl:98
  Test threw exception
  Expression: equality(a - c, a + -c)
  MethodError: objects of type Nothing are not callable
  Stacktrace:
   [1] (::fqPolyRepField)(b::fqPolyRepFieldElem)
     @ Nemo ~/.julia/packages/Nemo/Tj33G/src/flint/fq_nmod.jl:660
   [2] op(f::typeof(-), a::AlgClosureElem{fqPolyRepField}, b::AlgClosureElem{fqPolyRepField})
     @ Oscar.AlgClosureFp ~/work/Oscar.jl/Oscar.jl/src/Rings/AlgClosureFp.jl:117
   [3] -(a::AlgClosureElem{fqPolyRepField}, b::AlgClosureElem{fqPolyRepField})
     @ Oscar.AlgClosureFp ~/work/Oscar.jl/Oscar.jl/src/Rings/AlgClosureFp.jl:126
   [4] macro expansion
     @ ~/.julia/packages/AbstractAlgebra/lDlYU/test/Rings-conformance-tests.jl:98 [inlined]
   [5] macro expansion
     @ /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Test/src/Test.jl:1151 [inlined]
   [6] macro expansion
     @ ~/.julia/packages/AbstractAlgebra/lDlYU/test/Rings-conformance-tests.jl:70 [inlined]
   [7] macro expansion
     @ /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Test/src/Test.jl:1151 [inlined]
   [8] test_NCRing_interface(R::AlgClosure{fqPolyRepField}; reps::Int64)
     @ Main ~/.julia/packages/AbstractAlgebra/lDlYU/test/Rings-conformance-tests.jl:31

Full logs for 1.6 (https://github.com/oscar-system/Oscar.jl/actions/runs/5871596739/job/15921330205#step:6:1010) and nightly (https://github.com/oscar-system/Oscar.jl/actions/runs/5869443753/job/15914431074?pr=2644#step:6:1010).

cc @ThomasBreuer

ThomasBreuer · 2023-08-17T10:27:16Z

Funny.

Perhaps the simplest situation where a failure is reported is @test K(one(F2)) == K(one(F3)), because it happens outside the conformance test setup, and does not involve the creation of random elements:

Comparison for Finite field of degree 1 over GF(3): Error During Test at /home/runner/work/Oscar.jl/Oscar.jl/test/Rings/AlgClosureFp.jl:133
  Test threw exception
  Expression: K(one(F2)) == K(one(F3))
  MethodError: objects of type Nothing are not callable
  Stacktrace:
   [1] (::fqPolyRepField)(b::fqPolyRepFieldElem)
     @ Nemo ~/.julia/packages/Nemo/Tj33G/src/flint/fq_nmod.jl:660
   [2] op(f::typeof(==), a::AlgClosureElem{fqPolyRepField}, b::AlgClosureElem{fqPolyRepField})
     @ Oscar.AlgClosureFp ~/work/Oscar.jl/Oscar.jl/src/Rings/AlgClosureFp.jl:117
   [3] ==(a::AlgClosureElem{fqPolyRepField}, b::AlgClosureElem{fqPolyRepField})
     @ Oscar.AlgClosureFp ~/work/Oscar.jl/Oscar.jl/src/Rings/AlgClosureFp.jl:131
   [4] eval_test(evaluated::Expr, quoted::Expr, source::LineNumberNode, negate::Bool)
     @ Test /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Test/src/Test.jl:277
   [5] macro expansion
     @ ~/work/Oscar.jl/Oscar.jl/test/Rings/AlgClosureFp.jl:133 [inlined]
   [6] macro expansion
     @ /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Test/src/Test.jl:1226 [inlined]
   [7] macro expansion
     @ ~/work/Oscar.jl/Oscar.jl/test/Rings/AlgClosureFp.jl:125 [inlined]
   [8] macro expansion
     @ /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Test/src/Test.jl:1151 [inlined]
   [9] top-level scope
     @ ~/work/Oscar.jl/Oscar.jl/test/Rings/AlgClosureFp.jl:8

Up to now, I cannot reproduce the failures locally.
And I do not see where in the code the problem is; the test mentioned above should fail either always or never.

fingolfin · 2023-08-17T10:34:46Z

The line where the error happens is this:

function (a::fqPolyRepField)(b::fqPolyRepFieldElem)
    k = parent(b)
    da = degree(a)
    dk = degree(k)
    if k == a
        return b
    elseif dk < da
        da % dk != 0 && error("Coercion impossible")
        f = embed(k, a)
        return f(b)  # <--- error is here
    else
        dk % da != 0 && error("Coercion impossible")
        f = preimage_map(a, k)
        return f(b)
    end
end

So presumably embed returned nothing?

lgoettgens · 2023-08-17T11:00:49Z

Following @code_warntype, the place where nothing can be returned in embed is https://github.com/Nemocas/Nemo.jl/blob/407b0e0b5d3dc0d7ae9a7a1eb99b14b688e0a1a8/src/embedding/embedding.jl#L428
And looking at that function, there are cases where is_embedded returns nothing.

ThomasBreuer · 2023-08-17T11:11:51Z

My interpretation of the embed code in question is that the result of the intersections call is false only if the required embedding is known and hence is_embedded will return something.
Since the failure shows up only randomly, could the problem perhaps be that some cached values get lost?
Perhaps @thofma has an idea?

thofma · 2023-08-22T19:19:54Z

I am (still) looking at this. I could finally manage to reproduce it locally.

thofma · 2023-08-24T18:16:19Z

Here is how to reproduce it:

using Oscar, Test;
K = algebraic_closure(GF(3, 1));
data = [(1, [0]), (6, [0, 1, 2, 2, 1, 2]), (1, [0]), (4, [1, 0, 2, 0]), (8, [1, 0, 2, 1, 1, 2, 0, 0]), (6, [2, 0, 1, 2, 2, 1]), (8, [1, 1, 2, 2, 1, 2, 2, 0]), (2, [1, 2]), (1, [1]), (7, [0, 1, 2, 0, 0, 0, 2]), (8, [2, 1, 1, 2, 1, 0, 1, 0]), (5, [0, 1, 1, 1, 1]), (4, [2, 1, 0, 1]), (2, [2, 2]), (3, [1, 1, 0]), (1, [1]), (6, [1, 2, 1, 0, 2, 0]), (7, [1, 1, 1, 2, 2, 0, 2]), (3, [2, 2, 1]), (5, [0, 0, 0, 2, 1]), (2, [0, 0]), (1, [0]), (1, [1]), (3, [1, 2, 2]), (2, [1, 2]), (4, [0, 2, 2, 2]), (4, [0, 1, 2, 2]), (6, [2, 2, 1, 1, 0, 0]), (3, [0, 2, 2]), (4, [0, 0, 1, 0]), (4, [1, 0, 0, 2]), (8, [1, 0, 2, 2, 1, 2, 2, 1]), (6, [2, 2, 2, 2, 1, 0]), (4, [1, 1, 2, 1]), (2, [1, 0]), (2, [1, 0]), (5, [0, 0, 0, 0, 0]), (8, [2, 1, 1, 2, 2, 1, 0, 0]), (7, [1, 1, 2, 1, 2, 2, 1]), (6, [1, 2, 1, 1, 1, 1]), (4, [1, 2, 2, 1]), (1, [2]), (3, [1, 0, 0]), (3, [1, 1, 2]), (7, [2, 2, 2, 2, 0, 2, 0]), (2, [2, 2]), (2, [2, 1]), (7, [2, 1, 1, 0, 2, 1, 0]), (5, [2, 1, 0, 0, 1]), (8, [1, 1, 2, 2, 1, 1, 0, 0]), (1, [0]), (6, [0, 1, 2, 2, 1, 2]), (1, [0]), (4, [1, 0, 2, 0]), (8, [1, 0, 2, 1, 1, 2, 0, 0]), (6, [2, 0, 1, 2, 2, 1]), (8, [1, 1, 2, 2, 1, 2, 2, 0]), (2, [1, 2]), (1, [1]), (7, [0, 1, 2, 0, 0, 0, 2]), (8, [2, 1, 1, 2, 1, 0, 1, 0]), (5, [0, 1, 1, 1, 1]), (4, [2, 1, 0, 1]), (2, [2, 2]), (3, [1, 1, 0]), (1, [1]), (6, [1, 2, 1, 0, 2, 0]), (7, [1, 1, 1, 2, 2, 0, 2]), (3, [2, 2, 1]), (5, [0, 0, 0, 2, 1]), (2, [0, 0]), (1, [0]), (1, [1]), (3, [1, 2, 2]), (2, [1, 2]), (4, [0, 2, 2, 2]), (4, [0, 1, 2, 2]), (6, [2, 2, 1, 1, 0, 0]), (3, [0, 2, 2]), (4, [0, 0, 1, 0]), (4, [1, 0, 0, 2]), (8, [1, 0, 2, 2, 1, 2, 2, 1]), (6, [2, 2, 2, 2, 1, 0]), (4, [1, 1, 2, 1]), (2, [1, 0]), (2, [1, 0]), (5, [0, 0, 0, 0, 0]), (8, [2, 1, 1, 2, 2, 1, 0, 0]), (7, [1, 1, 2, 1, 2, 2, 1]), (6, [1, 2, 1, 1, 1, 1]), (4, [1, 2, 2, 1]), (1, [2]), (3, [1, 0, 0]), (3, [1, 1, 2]), (7, [2, 2, 2, 2, 0, 2, 0]), (2, [2, 2]), (2, [2, 1]), (7, [2, 1, 1, 0, 2, 1, 0]), (5, [2, 1, 0, 0, 1]), (8, [1, 1, 2, 2, 1, 1, 0, 0]), (1, [0]), (6, [0, 1, 2, 2, 1, 2]), (1, [0]), (4, [1, 0, 2, 0]), (8, [1, 0, 2, 1, 1, 2, 0, 0]), (6, [2, 0, 1, 2, 2, 1]), (8, [1, 1, 2, 2, 1, 2, 2, 0]), (2, [1, 2]), (1, [1]), (7, [0, 1, 2, 0, 0, 0, 2]), (8, [2, 1, 1, 2, 1, 0, 1, 0]), (5, [0, 1, 1, 1, 1]), (4, [2, 1, 0, 1]), (2, [2, 2]), (3, [1, 1, 0]), (1, [1]), (6, [1, 2, 1, 0, 2, 0]), (7, [1, 1, 1, 2, 2, 0, 2]), (3, [2, 2, 1]), (5, [0, 0, 0, 2, 1]), (2, [0, 0]), (1, [0]), (1, [1]), (3, [1, 2, 2]), (2, [1, 2]), (4, [0, 2, 2, 2]), (4, [0, 1, 2, 2]), (6, [2, 2, 1, 1, 0, 0]), (3, [0, 2, 2]), (4, [0, 0, 1, 0]), (4, [1, 0, 0, 2]), (8, [1, 0, 2, 2, 1, 2, 2, 1]), (6, [2, 2, 2, 2, 1, 0]), (4, [1, 1, 2, 1]), (2, [1, 0]), (2, [1, 0]), (5, [0, 0, 0, 0, 0]), (8, [2, 1, 1, 2, 2, 1, 0, 0]), (7, [1, 1, 2, 1, 2, 2, 1]), (6, [1, 2, 1, 1, 1, 1]), (4, [1, 2, 2, 1]), (1, [2]), (3, [1, 0, 0]), (3, [1, 1, 2]), (7, [2, 2, 2, 2, 0, 2, 0]), (2, [2, 2]), (2, [2, 1]), (7, [2, 1, 1, 0, 2, 1, 0]), (5, [2, 1, 0, 0, 1]), (8, [1, 1, 2, 2, 1, 1, 0, 0]), (7, [0, 1, 2, 2, 1, 1, 0]), (7, [0, 0, 2, 2, 0, 1, 1]), (5, [0, 0, 1, 1, 2]), (2, [0, 2]), (3, [1, 1, 1]), (1, [0]), (6, [2, 0, 1, 0, 2, 0]), (7, [2, 0, 1, 1, 2, 2, 1]), (2, [1, 2]), (1, [0]), (1, [2]), (6, [2, 1, 0, 2, 2, 2]), (3, [0, 0, 2]), (3, [1, 0, 0]), (5, [1, 2, 0, 0, 0]), (7, [0, 0, 1, 2, 0, 1, 0]), (6, [0, 2, 0, 0, 2, 0]), (2, [0, 0]), (2, [2, 1]), (6, [0, 2, 0, 0, 2, 1]), (6, [0, 1, 1, 2, 0, 0]), (6, [0, 0, 0, 2, 1, 1]), (5, [2, 2, 2, 2, 2]), (4, [2, 1, 2, 2]), (2, [0, 0]), (2, [1, 2]), (1, [0]), (8, [1, 2, 0, 0, 2, 2, 2, 0]), (6, [2, 2, 2, 2, 0, 1]), (7, [2, 2, 1, 2, 1, 2, 0]), (8, [2, 1, 2, 2, 2, 2, 1, 1]), (5, [1, 2, 1, 2, 2]), (2, [0, 2]), (5, [1, 1, 1, 0, 2]), (1, [1]), (7, [0, 2, 0, 1, 2, 2, 1]), (3, [0, 1, 2]), (6, [0, 2, 0, 0, 0, 0]), (3, [0, 0, 2]), (3, [0, 2, 2]), (6, [0, 0, 2, 1, 0, 1]), (7, [2, 2, 2, 2, 0, 0, 1]), (7, [2, 2, 2, 1, 1, 2, 2]), (3, [2, 0, 1]), (5, [0, 2, 2, 2, 2]), (4, [0, 1, 2, 2]), (1, [0]), (1, [2]), (1, [1]), (1, [1]), (1, [0]), (7, [1, 2, 1, 2, 2, 1, 1]), (4, [1, 2, 1, 2]), (1, [1]), (5, [0, 2, 1, 0, 2]), (7, [1, 2, 0, 0, 0, 1, 1]), (8, [0, 1, 1, 1, 1, 1, 0, 2]), (7, [0, 1, 0, 0, 1, 2, 2]), (1, [0]), (4, [0, 1, 2, 2]), (8, [2, 1, 2, 0, 1, 1, 1, 2]), (6, [0, 2, 2, 0, 2, 0]), (5, [1, 2, 1, 0, 1]), (1, [1]), (3, [0, 2, 2]), (2, [1, 2]), (8, [2, 0, 0, 2, 2, 2, 0, 1]), (4, [2, 1, 0, 0]), (4, [2, 2, 2, 0]), (3, [1, 1, 0]), (6, [2, 2, 2, 1, 1, 0]), (8, [1, 2, 0, 2, 2, 0, 1, 1]), (5, [0, 2, 2, 2, 2]), (7, [1, 0, 2, 2, 2, 1, 0]), (2, [2, 0]), (1, [1]), (3, [0, 2, 2]), (1, [1]), (1, [2]), (2, [2, 0]), (8, [1, 1, 0, 1, 0, 2, 2, 1]), (4, [1, 2, 0, 2]), (3, [0, 1, 2]), (4, [0, 1, 2, 0]), (1, [2]), (8, [0, 0, 1, 0, 0, 1, 1, 0]), (1, [1]), (7, [1, 2, 2, 1, 0, 0, 1]), (8, [2, 2, 0, 1, 1, 0, 1, 2]), (8, [0, 0, 2, 2, 2, 2, 2, 1]), (3, [2, 0, 2]), (4, [1, 1, 0, 1]), (8, [1, 0, 1, 0, 2, 1, 1, 1]), (2, [2, 2]), (5, [1, 1, 2, 2, 1]), (6, [1, 2, 0, 1, 2, 2]), (5, [1, 0, 0, 2, 2]), (6, [0, 0, 0, 2, 0, 2]), (2, [0, 2]), (8, [2, 0, 2, 1, 2, 1, 2, 2]), (3, [1, 2, 0]), (8, [1, 0, 0, 1, 2, 0, 0, 0]), (5, [2, 2, 0, 1, 1]), (5, [0, 0, 2, 1, 1]), (4, [0, 0, 0, 0]), (8, [1, 0, 1, 2, 2, 1, 2, 2]), (7, [2, 1, 0, 1, 1, 0, 0]), (6, [1, 2, 0, 1, 0, 0]), (1, [0]), (5, [0, 1, 1, 1, 2]), (4, [1, 2, 0, 0]), (7, [2, 2, 0, 1, 1, 2, 0]), (7, [2, 2, 0, 0, 2, 2, 1]), (5, [2, 1, 0, 0, 1]), (2, [1, 0]), (3, [0, 2, 1]), (2, [2, 0]), (6, [0, 2, 0, 1, 2, 1]), (8, [0, 0, 2, 0, 0, 0, 2, 0]), (5, [0, 1, 0, 2, 0]), (3, [2, 0, 1]), (2, [2, 0]), (4, [0, 2, 2, 2]), (7, [0, 0, 1, 2, 1, 0, 1]), (6, [1, 1, 2, 0, 1, 1]), (5, [1, 2, 1, 2, 1]), (8, [0, 2, 0, 0, 2, 2, 0, 2]), (3, [0, 0, 0]), (7, [1, 2, 1, 2, 1, 2, 2]), (7, [1, 0, 0, 0, 0, 1, 1]), (5, [1, 2, 2, 0, 1]), (4, [1, 1, 0, 0]), (1, [1]), (2, [0, 1]), (2, [1, 1]), (2, [0, 0]), (1, [2]), (5, [1, 0, 2, 1, 0]), (2, [2, 2]), (6, [1, 2, 1, 2, 1, 1]), (4, [1, 0, 1, 2]), (8, [2, 2, 1, 2, 1, 2, 0, 0]), (7, [2, 0, 0, 0, 0, 1, 2]), (6, [1, 0, 0, 0, 1, 0]), (4, [0, 0, 2, 0]), (6, [0, 1, 1, 0, 2, 0]), (5, [0, 0, 2, 0, 1]), (8, [1, 1, 2, 1, 2, 0, 0, 1]), (8, [1, 1, 0, 1, 1, 1, 1, 2]), (6, [2, 1, 0, 0, 0, 1]), (1, [0]), (6, [0, 1, 2, 2, 1, 2]), (1, [0]), (4, [1, 0, 2, 0]), (8, [1, 0, 2, 1, 1, 2, 0, 0]), (6, [2, 0, 1, 2, 2, 1]), (8, [1, 1, 2, 2, 1, 2, 2, 0]), (2, [1, 2]), (1, [1]), (7, [0, 1, 2, 0, 0, 0, 2]), (8, [2, 1, 1, 2, 1, 0, 1, 0]), (5, [0, 1, 1, 1, 1]), (4, [2, 1, 0, 1]), (2, [2, 2]), (3, [1, 1, 0]), (1, [1]), (6, [1, 2, 1, 0, 2, 0]), (7, [1, 1, 1, 2, 2, 0, 2]), (3, [2, 2, 1]), (5, [0, 0, 0, 2, 1]), (2, [0, 0]), (1, [0]), (1, [1]), (3, [1, 2, 2]), (2, [1, 2]), (4, [0, 2, 2, 2]), (4, [0, 1, 2, 2]), (6, [2, 2, 1, 1, 0, 0]), (3, [0, 2, 2]), (4, [0, 0, 1, 0]), (4, [1, 0, 0, 2]), (8, [1, 0, 2, 2, 1, 2, 2, 1]), (6, [2, 2, 2, 2, 1, 0]), (4, [1, 1, 2, 1]), (2, [1, 0]), (2, [1, 0]), (5, [0, 0, 0, 0, 0]), (8, [2, 1, 1, 2, 2, 1, 0, 0]), (7, [1, 1, 2, 1, 2, 2, 1]), (6, [1, 2, 1, 1, 1, 1]), (4, [1, 2, 2, 1]), (1, [2]), (3, [1, 0, 0]), (3, [1, 1, 2]), (7, [2, 2, 2, 2, 0, 2, 0]), (2, [2, 2]), (2, [2, 1]), (7, [2, 1, 1, 0, 2, 1, 0]), (5, [2, 1, 0, 0, 1]), (8, [1, 1, 2, 2, 1, 1, 0, 0]), (7, [0, 1, 2, 2, 1, 1, 0]), (7, [0, 0, 2, 2, 0, 1, 1]), (5, [0, 0, 1, 1, 2]), (2, [0, 2]), (3, [1, 1, 1]), (1, [0]), (6, [2, 0, 1, 0, 2, 0]), (7, [2, 0, 1, 1, 2, 2, 1]), (2, [1, 2]), (1, [0]), (1, [2]), (6, [2, 1, 0, 2, 2, 2]), (3, [0, 0, 2]), (3, [1, 0, 0]), (5, [1, 2, 0, 0, 0]), (7, [0, 0, 1, 2, 0, 1, 0]), (6, [0, 2, 0, 0, 2, 0]), (2, [0, 0]), (2, [2, 1]), (6, [0, 2, 0, 0, 2, 1]), (6, [0, 1, 1, 2, 0, 0]), (6, [0, 0, 0, 2, 1, 1]), (5, [2, 2, 2, 2, 2]), (4, [2, 1, 2, 2]), (2, [0, 0]), (2, [1, 2]), (1, [0]), (8, [1, 2, 0, 0, 2, 2, 2, 0]), (6, [2, 2, 2, 2, 0, 1]), (7, [2, 2, 1, 2, 1, 2, 0]), (8, [2, 1, 2, 2, 2, 2, 1, 1]), (5, [1, 2, 1, 2, 2]), (2, [0, 2]), (5, [1, 1, 1, 0, 2]), (1, [1]), (7, [0, 2, 0, 1, 2, 2, 1]), (3, [0, 1, 2]), (6, [0, 2, 0, 0, 0, 0]), (3, [0, 0, 2]), (3, [0, 2, 2]), (6, [0, 0, 2, 1, 0, 1]), (7, [2, 2, 2, 2, 0, 0, 1]), (7, [2, 2, 2, 1, 1, 2, 2]), (3, [2, 0, 1]), (5, [0, 2, 2, 2, 2]), (4, [0, 1, 2, 2]), (1, [0]), (1, [2]), (1, [1]), (1, [1]), (1, [0]), (7, [1, 2, 1, 2, 2, 1, 1]), (4, [1, 2, 1, 2]), (1, [1]), (5, [0, 2, 1, 0, 2]), (7, [1, 2, 0, 0, 0, 1, 1]), (8, [0, 1, 1, 1, 1, 1, 0, 2]), (7, [0, 1, 0, 0, 1, 2, 2]), (1, [0]), (4, [0, 1, 2, 2]), (8, [2, 1, 2, 0, 1, 1, 1, 2]), (6, [0, 2, 2, 0, 2, 0]), (5, [1, 2, 1, 0, 1]), (1, [1]), (3, [0, 2, 2]), (2, [1, 2]), (8, [2, 0, 0, 2, 2, 2, 0, 1]), (4, [2, 1, 0, 0]), (4, [2, 2, 2, 0]), (3, [1, 1, 0]), (6, [2, 2, 2, 1, 1, 0]), (8, [1, 2, 0, 2, 2, 0, 1, 1]), (5, [0, 2, 2, 2, 2]), (7, [1, 0, 2, 2, 2, 1, 0]), (2, [2, 0]), (1, [1]), (3, [0, 2, 2]), (1, [1]), (1, [2]), (2, [2, 0]), (8, [1, 1, 0, 1, 0, 2, 2, 1]), (4, [1, 2, 0, 2]), (3, [0, 1, 2]), (4, [0, 1, 2, 0]), (1, [2]), (8, [0, 0, 1, 0, 0, 1, 1, 0]), (1, [1]), (7, [1, 2, 2, 1, 0, 0, 1]), (8, [2, 2, 0, 1, 1, 0, 1, 2]), (8, [0, 0, 2, 2, 2, 2, 2, 1]), (3, [2, 0, 2]), (4, [1, 1, 0, 1]), (8, [1, 0, 1, 0, 2, 1, 1, 1]), (2, [2, 2]), (5, [1, 1, 2, 2, 1]), (6, [1, 2, 0, 1, 2, 2]), (5, [1, 0, 0, 2, 2]), (6, [0, 0, 0, 2, 0, 2]), (2, [0, 2]), (8, [2, 0, 2, 1, 2, 1, 2, 2]), (1, [0]), (6, [0, 1, 2, 2, 1, 2]), (1, [0]), (4, [1, 0, 2, 0]), (8, [1, 0, 2, 1, 1, 2, 0, 0]), (6, [2, 0, 1, 2, 2, 1]), (8, [1, 1, 2, 2, 1, 2, 2, 0]), (2, [1, 2]), (1, [1]), (7, [0, 1, 2, 0, 0, 0, 2]), (8, [2, 1, 1, 2, 1, 0, 1, 0]), (5, [0, 1, 1, 1, 1]), (4, [2, 1, 0, 1]), (2, [2, 2]), (3, [1, 1, 0]), (1, [1]), (6, [1, 2, 1, 0, 2, 0]), (7, [1, 1, 1, 2, 2, 0, 2]), (3, [2, 2, 1]), (5, [0, 0, 0, 2, 1]), (2, [0, 0]), (1, [0]), (1, [1]), (3, [1, 2, 2]), (2, [1, 2]), (4, [0, 2, 2, 2]), (4, [0, 1, 2, 2]), (6, [2, 2, 1, 1, 0, 0]), (3, [0, 2, 2]), (4, [0, 0, 1, 0]), (4, [1, 0, 0, 2]), (8, [1, 0, 2, 2, 1, 2, 2, 1]), (6, [2, 2, 2, 2, 1, 0]), (4, [1, 1, 2, 1]), (2, [1, 0]), (2, [1, 0]), (5, [0, 0, 0, 0, 0]), (8, [2, 1, 1, 2, 2, 1, 0, 0]), (7, [1, 1, 2, 1, 2, 2, 1]), (6, [1, 2, 1, 1, 1, 1]), (4, [1, 2, 2, 1]), (1, [2]), (3, [1, 0, 0]), (3, [1, 1, 2]), (7, [2, 2, 2, 2, 0, 2, 0]), (2, [2, 2]), (2, [2, 1]), (7, [2, 1, 1, 0, 2, 1, 0]), (5, [2, 1, 0, 0, 1]), (8, [1, 1, 2, 2, 1, 1, 0, 0]), (7, [0, 1, 2, 2, 1, 1, 0]), (7, [0, 0, 2, 2, 0, 1, 1]), (5, [0, 0, 1, 1, 2]), (2, [0, 2]), (3, [1, 1, 1]), (1, [0]), (6, [2, 0, 1, 0, 2, 0]), (7, [2, 0, 1, 1, 2, 2, 1]), (2, [1, 2]), (1, [0]), (1, [2]), (6, [2, 1, 0, 2, 2, 2]), (3, [0, 0, 2]), (3, [1, 0, 0]), (5, [1, 2, 0, 0, 0]), (7, [0, 0, 1, 2, 0, 1, 0]), (6, [0, 2, 0, 0, 2, 0]), (2, [0, 0]), (2, [2, 1]), (6, [0, 2, 0, 0, 2, 1]), (6, [0, 1, 1, 2, 0, 0]), (6, [0, 0, 0, 2, 1, 1]), (5, [2, 2, 2, 2, 2]), (4, [2, 1, 2, 2]), (2, [0, 0]), (2, [1, 2]), (1, [0]), (8, [1, 2, 0, 0, 2, 2, 2, 0]), (6, [2, 2, 2, 2, 0, 1]), (7, [2, 2, 1, 2, 1, 2, 0]), (8, [2, 1, 2, 2, 2, 2, 1, 1]), (5, [1, 2, 1, 2, 2]), (2, [0, 2]), (5, [1, 1, 1, 0, 2]), (1, [1]), (7, [0, 2, 0, 1, 2, 2, 1]), (3, [0, 1, 2]), (6, [0, 2, 0, 0, 0, 0]), (3, [0, 0, 2]), (3, [0, 2, 2]), (6, [0, 0, 2, 1, 0, 1]), (7, [2, 2, 2, 2, 0, 0, 1]), (7, [2, 2, 2, 1, 1, 2, 2]), (3, [2, 0, 1]), (5, [0, 2, 2, 2, 2]), (4, [0, 1, 2, 2]), (1, [0]), (1, [2]), (1, [1]), (1, [1]), (1, [0]), (6, [0, 1, 2, 2, 1, 2]), (1, [0]), (4, [1, 0, 2, 0]), (8, [1, 0, 2, 1, 1, 2, 0, 0]), (6, [2, 0, 1, 2, 2, 1]), (8, [1, 1, 2, 2, 1, 2, 2, 0]), (2, [1, 2]), (1, [1]), (7, [0, 1, 2, 0, 0, 0, 2]), (8, [2, 1, 1, 2, 1, 0, 1, 0]), (5, [0, 1, 1, 1, 1]), (4, [2, 1, 0, 1]), (2, [2, 2]), (3, [1, 1, 0]), (1, [1]), (6, [1, 2, 1, 0, 2, 0]), (7, [1, 1, 1, 2, 2, 0, 2]), (3, [2, 2, 1]), (5, [0, 0, 0, 2, 1]), (2, [0, 0]), (1, [0]), (1, [1]), (3, [1, 2, 2]), (2, [1, 2]), (4, [0, 2, 2, 2]), (4, [0, 1, 2, 2]), (6, [2, 2, 1, 1, 0, 0]), (3, [0, 2, 2]), (4, [0, 0, 1, 0]), (4, [1, 0, 0, 2]), (8, [1, 0, 2, 2, 1, 2, 2, 1]), (6, [2, 2, 2, 2, 1, 0]), (4, [1, 1, 2, 1]), (2, [1, 0]), (2, [1, 0]), (5, [0, 0, 0, 0, 0]), (8, [2, 1, 1, 2, 2, 1, 0, 0]), (7, [1, 1, 2, 1, 2, 2, 1]), (6, [1, 2, 1, 1, 1, 1]), (4, [1, 2, 2, 1]), (1, [2]), (3, [1, 0, 0]), (3, [1, 1, 2]), (7, [2, 2, 2, 2, 0, 2, 0]), (2, [2, 2]), (2, [2, 1]), (7, [2, 1, 1, 0, 2, 1, 0]), (5, [2, 1, 0, 0, 1]), (8, [1, 1, 2, 2, 1, 1, 0, 0])];
global i = 1;
function test_elem(K::AlgClosure{T}) where T <: FinField
  global i;
  j = i;
  i = i + 1;
  K(ext_of_degree(K, data[j][1])(data[j][2]));
end
include(joinpath(pathof(AbstractAlgebra), "..", "..", "test", "Rings-conformance-tests.jl"));
test_Field_interface(K); # this will error
elts = [ K(ext_of_degree(K, d[1])(d[2])) for d in data];
a = elts[8]; b = elts[12]; c = elts[2];
aa = a + b; # aa + c will error
ad = Oscar.data(aa); bd = Oscar.data(c);
l = lcm(degree(parent(ad)), degree(parent(bd)))
k = ext_of_degree(parent(a), l)
embed(parent(ad), k) # this returns nothing, which is bad

It is unrelated to caching and looks more like a bug in the embedding code (the theory of which is "described" here: https://dl.acm.org/doi/abs/10.1145/3282678.3282682). Because of its recursive nature, it is a bit tedious to follow. Feel free to look at it. Otherwise I will discuss it with @fieker once he is back from holiday.

ThomasBreuer · 2023-08-24T19:48:01Z

Thanks @thofma, this looks very interesting.

thofma · 2023-08-25T10:24:35Z

Here are some bread crumps, so that I don't forget about it:

embed(parent(ad), k)

will call

intersections(parent(ad), k)

(https://github.com/Nemocas/Nemo.jl/blob/master/src/embedding/embedding.jl#L301)
Since k has a subfield of degree 10 (distinct from parent(ad)), this will hit
https://github.com/Nemocas/Nemo.jl/blob/fd27c979490a21b16c119fee4e6e4d85ad31ea4f/src/embedding/embedding.jl#L325-L327
Hence we call embed(parent(ad), kk) where kk = k.subfields[10][1]. By "transitivity", this should also compute an embedding embed(parent(ad), k), but it does not. The call embed(parent(ad), kk) will hit the branch
https://github.com/Nemocas/Nemo.jl/blob/fd27c979490a21b16c119fee4e6e4d85ad31ea4f/src/embedding/embedding.jl#L395-L400
which just returns a map parent(ad) -> kk. But in this branch, no transitive closure is computed. I don't know whether the problem is

that this branch does not compute the transitive closure, or
that the lattice is already in an inconsistent state.
(I tried fixing 1., but ran in an infinite recursion.)

fingolfin · 2023-08-28T09:04:17Z

OK, part of the issue is indeed this function (following the hint by @lgoettgens) in this code:

function is_embedded(k::T, K::T) where T <: FinField


    d = degree(K)
    ov = overfields(k)


    # We look for an embedding that has k as domain and K as codomain


    if haskey(ov, d)
        for f in ov[d]
            if domain(f) == k && codomain(f) == K
                return f
            end
        end
    end
end

Clearly this function returns a cached value if available -- and otherwise nothing (funnily it never returns a boolean, despite being called is_embedded ;-) -- I guess we should rename it).

So it seems the return value of intersections, which is needmore, is not reliable.

Perhaps it suffices to replace the check for needmore by instead first calling is_embedded; if it gives something, return that, if not, set needmore = true.

fingolfin · 2023-08-30T09:54:27Z

This should be fixed by PR #2739 ; however, there are more issues hidden in the subfield lattice code, which need to be addressed. We asked @mjrodgers to look into some of this.

HereAround · 2023-08-30T12:53:30Z

I am still seeing this sort of failure in run https://github.com/oscar-system/Oscar.jl/actions/runs/6023945049/job/16341680795?pr=2741. The PR has been rebased to the latest master in the morning and ran around noon today. Please have a brief look.

benlorenz · 2023-09-04T14:33:12Z

This error looks similar, from today (#2764):

Arithmetic for Finite field of degree 1 over GF(3): Error During Test at /Users/runner/work/Oscar.jl/Oscar.jl/test/Rings/AlgClosureFp.jl:89
  Test threw exception
  Expression: a * (b + c) == a * b + a * c
  MethodError: objects of type Nothing are not callable
  Stacktrace:
   [1] (::FqField)(b::FqFieldElem)
     @ Nemo ~/.julia/packages/Nemo/Tj33G/src/flint/fq_default_extended.jl:703
   [2] op(f::typeof(*), a::AlgClosureElem{FqField}, b::AlgClosureElem{FqField})
     @ Oscar.AlgClosureFp ~/work/Oscar.jl/Oscar.jl/src/Rings/AlgClosureFp.jl:129
   [3] *(a::AlgClosureElem{FqField}, b::AlgClosureElem{FqField})
     @ Oscar.AlgClosureFp ~/work/Oscar.jl/Oscar.jl/src/Rings/AlgClosureFp.jl:140
   [4] macro expansion
     @ ~/hostedtoolcache/julia/1.9.3/x64/share/julia/stdlib/v1.9/Test/src/Test.jl:478 [inlined]
   [5] macro expansion
     @ ~/work/Oscar.jl/Oscar.jl/test/Rings/AlgClosureFp.jl:89 [inlined]
   [6] macro expansion
     @ ~/hostedtoolcache/julia/1.9.3/x64/share/julia/stdlib/v1.9/Test/src/Test.jl:1586 [inlined]
   [7] macro expansion
     @ ~/work/Oscar.jl/Oscar.jl/test/Rings/AlgClosureFp.jl:77 [inlined]
   [8] macro expansion
     @ ~/hostedtoolcache/julia/1.9.3/x64/share/julia/stdlib/v1.9/Test/src/Test.jl:1498 [inlined]
   [9] top-level scope
     @ ~/work/Oscar.jl/Oscar.jl/test/Rings/AlgClosureFp.jl:8

fingolfin · 2023-09-20T10:18:13Z

I haven't seen this bug recently, so maybe it is fixed (or at least this aspect of it) after all?

benlorenz · 2023-09-20T10:25:12Z

Not really, it happened again here, 2 hours ago on master:

Basic functions: Error During Test at /Users/runner/.julia/packages/AbstractAlgebra/Ry0na/test/Rings-conformance-tests.jl:96
  Test threw exception
  Expression: equality((a + b) + c, a + (b + c))
  MethodError: objects of type Nothing are not callable
  Stacktrace:
   [1] (::fqPolyRepField)(b::fqPolyRepFieldElem)
     @ Nemo ~/.julia/packages/Nemo/yGn7K/src/flint/fq_nmod.jl:660
   [2] op(f::typeof(+), a::AlgClosureElem{fqPolyRepField}, b::AlgClosureElem{fqPolyRepField})
     @ Oscar.AlgClosureFp ~/work/Oscar.jl/Oscar.jl/src/Rings/AlgClosureFp.jl:129
   [3] +(a::AlgClosureElem{fqPolyRepField}, b::AlgClosureElem{fqPolyRepField})
     @ Oscar.AlgClosureFp ~/work/Oscar.jl/Oscar.jl/src/Rings/AlgClosureFp.jl:132
   [4] macro expansion
     @ ~/hostedtoolcache/julia/1.9.3/x64/share/julia/stdlib/v1.9/Test/src/Test.jl:478 [inlined]
   [5] macro expansion
     @ ~/.julia/packages/AbstractAlgebra/Ry0na/test/Rings-conformance-tests.jl:96 [inlined]
   [6] macro expansion
     @ ~/hostedtoolcache/julia/1.9.3/x64/share/julia/stdlib/v1.9/Test/src/Test.jl:1498 [inlined]
   [7] macro expansion
     @ ~/.julia/packages/AbstractAlgebra/Ry0na/test/Rings-conformance-tests.jl:70 [inlined]
   [8] macro expansion
     @ ~/hostedtoolcache/julia/1.9.3/x64/share/julia/stdlib/v1.9/Test/src/Test.jl:1498 [inlined]
   [9] test_NCRing_interface(R::AlgClosure{fqPolyRepField}; reps::Int64)
     @ Main ~/.julia/packages/AbstractAlgebra/Ry0na/test/Rings-conformance-tests.jl:31

and here as well, 10 hours ago:

Arithmetic for Finite field of degree 1 over GF(3): Error During Test at /Users/runner/work/Oscar.jl/Oscar.jl/test/Rings/AlgClosureFp.jl:89
  Test threw exception
  Expression: a * (b + c) == a * b + a * c
  MethodError: objects of type Nothing are not callable
  Stacktrace:
   [1] (::FqField)(b::FqFieldElem)
     @ Nemo ~/.julia/packages/Nemo/yGn7K/src/flint/fq_default_extended.jl:705
   [2] op(f::typeof(+), a::AlgClosureElem{FqField}, b::AlgClosureElem{FqField})
     @ Oscar.AlgClosureFp ~/work/Oscar.jl/Oscar.jl/src/Rings/AlgClosureFp.jl:129
   [3] +(a::AlgClosureElem{FqField}, b::AlgClosureElem{FqField})
     @ Oscar.AlgClosureFp ~/work/Oscar.jl/Oscar.jl/src/Rings/AlgClosureFp.jl:132
   [4] macro expansion
     @ ~/hostedtoolcache/julia/1.9.3/x64/share/julia/stdlib/v1.9/Test/src/Test.jl:478 [inlined]
   [5] macro expansion
     @ ~/work/Oscar.jl/Oscar.jl/test/Rings/AlgClosureFp.jl:89 [inlined]
   [6] macro expansion
     @ ~/hostedtoolcache/julia/1.9.3/x64/share/julia/stdlib/v1.9/Test/src/Test.jl:1586 [inlined]
   [7] macro expansion
     @ ~/work/Oscar.jl/Oscar.jl/test/Rings/AlgClosureFp.jl:77 [inlined]
   [8] macro expansion
     @ ~/hostedtoolcache/julia/1.9.3/x64/share/julia/stdlib/v1.9/Test/src/Test.jl:1498 [inlined]
   [9] top-level scope
     @ ~/work/Oscar.jl/Oscar.jl/test/Rings/AlgClosureFp.jl:8

One is for FqField and the other one for fqPolyRepField.

mjrodgers · 2023-11-08T10:14:29Z

Just an update on this, I have been taking a look on it and reading about how this lattice of embedded subfields is handled in Magma. As for these randomized tests failing, it is something I haven't been able to recreate at the moment.

lgoettgens added bug Something isn't working topic: rings labels Aug 17, 2023

fingolfin mentioned this issue Aug 21, 2023

more on Betti diagrams #2706

Merged

lgoettgens mentioned this issue Aug 23, 2023

FreeAssAlg-serialisation #2716

Merged

fieker mentioned this issue Aug 28, 2023

make use of the subfield lattice to not have double entries #2739

Merged

fingolfin closed this as completed Aug 30, 2023

HereAround reopened this Aug 30, 2023

fingolfin mentioned this issue Sep 26, 2023

Call Oscar.randseed! at start of test suite #2809

Merged

This was referenced Oct 5, 2023

Try to make AlgClosureFp tests fail less often #2881

Closed

Disable AlgClosureFp tests for now #2888

Merged

benlorenz mentioned this issue Oct 9, 2023

Tests: automatically run all test files #2810

Merged

mjrodgers mentioned this issue Nov 20, 2023

Make sure embeddings are computed and returned Nemocas/Nemo.jl#1579

Merged

thofma closed this as completed in Nemocas/Nemo.jl#1579 Nov 21, 2023

lgoettgens mentioned this issue Nov 21, 2023

Revert "Disable AlgClosureFp tests for now (#2888)" #3029

Merged

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Randomized tests failing for `AlgClosure{fqPolyRepField}` #2691

Randomized tests failing for `AlgClosure{fqPolyRepField}` #2691

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Randomized tests failing for AlgClosure{fqPolyRepField} #2691

Randomized tests failing for AlgClosure{fqPolyRepField} #2691

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Randomized tests failing for `AlgClosure{fqPolyRepField}` #2691

Randomized tests failing for `AlgClosure{fqPolyRepField}` #2691

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