Support for arbitrary ring morphisms with number field domains (#1324)

thofma · Dec 15, 2023 · 1a8328c · 1a8328c · thofma · Dec 15, 2023
1 parent 97bd536
commit 1a8328c
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Showing 3 changed files with 32 additions and 7 deletions.
diff --git a/Project.toml b/Project.toml
@@ -1,6 +1,6 @@
 name = "Hecke"
 uuid = "3e1990a7-5d81-5526-99ce-9ba3ff248f21"
-version = "0.23.2-DEV"
+version = "0.23.2"
 
 [deps]
 AbstractAlgebra = "c3fe647b-3220-5bb0-a1ea-a7954cac585d"

diff --git a/src/Map/NumField.jl b/src/Map/NumField.jl
@@ -140,7 +140,7 @@ end
 function hom(K::S, L::T, x...; inverse = nothing,
                                check::Bool = true,
                                compute_inverse = false) where {S <: Union{NumField, QQField},
-                                                               T <: NumField}
+                                                               T <: Ring}
   header = MapHeader(K, L)
 
   #if length(x) == 0
@@ -166,7 +166,7 @@ function hom(K::S, L::T, x...; inverse = nothing,
                        typeof(inverse_data)}(header, image_data, inverse_data)
 
   else
-    z = NumFieldMor{S, T, typeof(image_data), map_data_type(L, K)}()
+      z = NumFieldMor{S, T, typeof(image_data), map_data_type(L, K)}()
   end
 
   z.header = header
@@ -245,9 +245,9 @@ mutable struct MapDataFromAnticNumberField{T}
 end
 
 # Helper functions to create the type
-map_data_type(K::AnticNumberField, L::Union{NumField, QQField}) = map_data_type(AnticNumberField, typeof(L))
+map_data_type(K::AnticNumberField, L::Union{NumField, QQField, Ring}) = map_data_type(AnticNumberField, typeof(L))
 
-map_data_type(::Type{AnticNumberField}, T::Type{S}) where {S <: Union{NumField, QQField}} = MapDataFromAnticNumberField{elem_type(T)}
+map_data_type(::Type{AnticNumberField}, T::Type{S}) where {S <: Union{NumField, QQField, Ring}} = MapDataFromAnticNumberField{elem_type(T)}
 
 # Test if data u, v specfiying a map K -> L define the same morphism
 function _isequal(K, L, u::MapDataFromAnticNumberField{T},
@@ -272,7 +272,7 @@ end
 #
 map_data(K::AnticNumberField, L, ::Bool) = MapDataFromAnticNumberField{elem_type(L)}(true)
 
-function map_data(K::AnticNumberField, L, x::NumFieldElem; check = true)
+function map_data(K::AnticNumberField, L, x::RingElement; check = true)
   if parent(x) === L
     xx = x
   else
@@ -322,7 +322,7 @@ function map_data_type(T::Type{<: NfRel}, L::Type{<:Any})
   MapDataFromNfRel{elem_type(L), map_data_type(base_field_type(T), L)}
 end
 
-map_data_type(K::NfRel, L::NumField) = map_data_type(typeof(K), typeof(L))
+map_data_type(K::NfRel, L::Ring) = map_data_type(typeof(K), typeof(L))
 
 # Test if data u, v specfiying a map K -> L define the same morphism
 function _isequal(K, L, u::MapDataFromNfRel{T, S}, v::MapDataFromNfRel{T, S}) where {T, S}
@@ -1030,6 +1030,16 @@ end
 
 Base.hash(f::NumFieldMor, h::UInt) = hash(f.image_data, domain(f), codomain(f), h)
 
+################################################################################
+#
+#  Catch all for morphisms into arbitrary rings
+#
+################################################################################
+
+map_data_type(::Type{<: Any}, x) = Nothing
+
+map_data_type(R, x) = map_data_type(typeof(R), typeof(x))
+
 ################################################################################
 #
 #  Restriction

diff --git a/test/Map/NumField.jl b/test/Map/NumField.jl
@@ -347,4 +347,19 @@
     D = Dict(f => 1)
     @test haskey(D, g)
   end
+
+  # Maps into arbitrary rings
+  begin
+    K, a = quadratic_field(-1);
+    Kx, x = K["x"]
+    h = @inferred hom(K, Kx, Kx(a))
+    @test h(a + 1) == Kx(a + 1)
+
+    Qx, x = QQ["x"]
+    K, a = number_field([x - 1, x - 2])
+    QQy, y = polynomial_ring(QQ, 2)
+    @test_throws ErrorException hom(K, QQy, [0, 0])
+    h = @inferred hom(K, QQy, [1, 2])
+    @test h(a[1] + a[2]) == QQy(3)
+  end
 end