fix: don't use polynomial rings over zero rings

thofma · Nov 14, 2024 · ddf1e30 · ddf1e30
1 parent 0d6625a
commit ddf1e30
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diff --git a/src/Misc/nmod_poly.jl b/src/Misc/nmod_poly.jl
@@ -199,6 +199,9 @@ function resultant_ideal_pp(f::PolyRingElem{T}, g::PolyRingElem{T}) where T <: R
       s = gcd(lift(res), pn)
       if !isone(s)
         new_pn = divexact(pn, s)
+        if is_one(new_pn)
+          return zero(R)
+        end
         R1 = residue_ring(ZZ, S(new_pn), cached = false)[1]
         R1t = polynomial_ring(R1, "y", cached = false)[1]
         f2 = R1t(T[R1(lift(coeff(f, i))) for i = 0:degree(f)])

diff --git a/src/NumFieldOrd/NfOrd/Ideal/Ideal.jl b/src/NumFieldOrd/NfOrd/Ideal/Ideal.jl
@@ -1053,6 +1053,9 @@ function _minmod_easy(a::ZZRingElem, b::AbsSimpleNumFieldOrderElem)
 end
 
 function _minmod_easy_pp(a::ZZRingElem, b::AbsSimpleNumFieldOrderElem)
+  if isone(a)
+    return one(a)
+  end
   Zk = parent(b)
   k = number_field(Zk)
   if fits(Int, a)