Bugfix for conversions

src/FeynmanDiagram.jl

@@ -112,7 +112,7 @@ export Graph, FeynmanGraph, FeynmanProperties
 
 export isequiv, drop_topology, is_external, is_internal, diagram_type, orders, vertices, topology
 export external_legs, external_indices, external_operators, external_labels
-export linear_combination, feynman_diagram, propagator, interaction, external_vertex
+export multi_product, linear_combination, feynman_diagram, propagator, interaction, external_vertex
 # export DiagramType, Interaction, ExternalVertex, Propagator, SelfEnergy, VertexDiag, GreenDiag, GenericDiag
 
 # export standardize_order!

src/computational_graph/ComputationalGraph.jl

@@ -29,7 +29,7 @@ export Graph, FeynmanGraph, FeynmanProperties
 
 export isequiv, drop_topology, is_external, is_internal, diagram_type, orders, vertices, topology
 export external_legs, external_indices, external_operators, external_labels
-export linear_combination, feynman_diagram, propagator, interaction, external_vertex
+export multi_product, linear_combination, feynman_diagram, propagator, interaction, external_vertex
 
 # export Prod, Sum
 # export DiagramType, Interaction, ExternalVertex, Propagator, SelfEnergy, VertexDiag, GreenDiag, GenericDiag

src/computational_graph/conversions.jl

@@ -1,18 +1,18 @@
 
 """
-    function Base.convert(Graph, g::FeynmanGraph)
+    function Base.convert(::Type{G}, g::FeynmanGraph{F,W}) where {F,W,G<:Graph}
     
     Converts a FeynmanGraph `g` into a Graph, discarding its Feynman properties.
     After conversion, graph `g` is no longer guaranteed to be a valid (group of) Feynman diagram(s).
 
     # Arguments:
     - `g`  computational graph
 """
-function Base.convert(::Type{Graph{F,W}}, g::FeynmanGraph{F,W}) where {F,W}
-    return Graph{F,W}(g.subgraphs; subgraph_factors=g.subgraph_factors, name=g.name, operator=g.operator, orders=g.orders, factor=g.factor, weight=g.weight)
+function Base.convert(::Type{G}, g::FeynmanGraph{F,W}) where {F,W,G<:Graph}
+    return Graph(g.subgraphs; subgraph_factors=g.subgraph_factors, name=g.name, operator=g.operator(), orders=g.orders, ftype=F, wtype=W, factor=g.factor, weight=g.weight)
 end
 
-function Base.convert(::Type{FeynmanGraph{F,W}}, g::Graph{F,W}) where {F,W}
+function Base.convert(::Type{FeynmanGraph}, g::Graph{F,W}) where {F,W}
     error(
         "A set of Feynman properties (operator vertices, topology, etc.) must be specified to convert an object of type Graph to FeynmanGraph. " *
         "Please use constructor `FeynmanGraph(g::Graph, properties::FeynmanProperties)` instead."
@@ -33,5 +33,5 @@ Base.:*(g1::Graph, g2::FeynmanGraph) = error("Multiplication of Feynman graphs i
 Base.:*(g1::FeynmanGraph, g2::Graph) = error("Multiplication of Feynman graphs is not well defined!")
 Base.:+(g1::Graph{F,W}, g2::FeynmanGraph{F,W}) where {F,W} = Base.:+(Base.promote(g1, g2)...)
 Base.:+(g1::FeynmanGraph{F,W}, g2::Graph{F,W}) where {F,W} = Base.:+(Base.promote(g1, g2)...)
-Base.:-(g1::Graph{F,W}, g2::FeynmanGraph{F,W}) where {F,W} = Base.:+(Base.promote(g1, g2)...)
-Base.:-(g1::FeynmanGraph{F,W}, g2::Graph{F,W}) where {F,W} = Base.:+(Base.promote(g1, g2)...)
+Base.:-(g1::Graph{F,W}, g2::FeynmanGraph{F,W}) where {F,W} = Base.:-(Base.promote(g1, g2)...)
+Base.:-(g1::FeynmanGraph{F,W}, g2::Graph{F,W}) where {F,W} = Base.:-(Base.promote(g1, g2)...)

src/computational_graph/feynmangraph.jl

@@ -162,10 +162,10 @@ mutable struct FeynmanGraph{F,W} <: AbstractGraph # FeynmanGraph
     - `g`  computational graph
     - `properties::FeynmanProperties`  diagrammatic properties, e.g., the operator vertices and topology 
     """
-    function FeynmanGraph(g::Graph, properties::FeynmanProperties)
+    function FeynmanGraph(g::Graph{F,W}, properties::FeynmanProperties) where {F,W}
         @assert length(properties.external_indices) == length(properties.external_legs)
         # @assert allunique(subgraphs) "all subgraphs must be distinct."
-        return new{ftype,wtype}(uid(), g.name, g.orders, properties, g.subgraphs, g.subgraph_factors, typeof(g.operator), g.factor, g.weight)
+        return new{F,W}(uid(), g.name, g.orders, properties, g.subgraphs, g.subgraph_factors, g.operator, g.factor, g.weight)
     end
 end
 

test/computational_graph.jl

@@ -19,18 +19,18 @@ Graphs.unary_istrivial(::Type{O}) where {O<:Union{O1,O2,O3}} = true
         subgraph_factors::Vector{Float64}
         factor::Float64
         weight::Float64
-        function ConcreteGraph(subgraphs=[]; name="", orders=zeros(Int, 0), operator=O, subgraph_factors=[], factor=1.0, weight=1.0)
-            return new(Graphs.uid(), name, orders, operator, subgraphs, subgraph_factors, factor, weight)
+        function ConcreteGraph(subgraphs=[]; name="", orders=zeros(Int, 0), operator=O(), subgraph_factors=[], factor=1.0, weight=1.0)
+            return new(Graphs.uid(), name, orders, typeof(operator), subgraphs, subgraph_factors, factor, weight)
         end
     end
 
     Graphs.uidreset()
-    g1 = ConcreteGraph(; operator=O1)
-    g2 = ConcreteGraph(; operator=O2)
-    g3 = ConcreteGraph(; operator=O3)
-    g = ConcreteGraph([g1, g2, g3]; subgraph_factors=[2, 3, 5], operator=O)
-    gp = ConcreteGraph([g1, g2, g3]; subgraph_factors=[2, 3, 5], operator=O)
-    h = ConcreteGraph([g1, g2, g3]; name="h", subgraph_factors=[2, 3, 5], operator=O)
+    g1 = ConcreteGraph(; operator=O1())
+    g2 = ConcreteGraph(; operator=O2())
+    g3 = ConcreteGraph(; operator=O3())
+    g = ConcreteGraph([g1, g2, g3]; subgraph_factors=[2, 3, 5], operator=O())
+    gp = ConcreteGraph([g1, g2, g3]; subgraph_factors=[2, 3, 5], operator=O())
+    h = ConcreteGraph([g1, g2, g3]; name="h", subgraph_factors=[2, 3, 5], operator=O())
 
     # weight(g::AbstractGraph) is an abstract method
     @test isnothing(Graphs.weight(ConcreteGraph()))
@@ -853,6 +853,67 @@ end
     end
 end
 
+@testset verbose = true "Conversions" begin
+    # Test constructor for FeynmanGraph from Graph and FeynmanProperties
+    g = Graph([]; factor=-1.0, operator=Graphs.Sum())
+    g1 = Graph([]; operator=O1())
+    g2 = Graph([]; operator=O2())
+    g_feyn = propagator(𝑓⁺(1)𝑓⁻(2))  # equivalent to g after conversion
+    g_feyn_conv = FeynmanGraph(g, g_feyn.properties)
+    @test isequiv(g_feyn, g_feyn_conv, :id)
+
+    # Test automatic FeynmanGraph -> Graph conversion
+    g_conv::Graph = g_feyn
+    @test isequiv(g, g_conv, :id)
+
+    # Test automatic FeynmanGraph -> Graph promotion in arithmetic operations
+    conversion_successful = true
+    local l1, l2, l3, l4, l5, l6, l7, r7, l8, r8
+    try
+        l1 = g_feyn + g1
+        l2 = g_feyn - g1
+        l3 = linear_combination(g_feyn, g1, 2, 3)
+        l4 = linear_combination(g_feyn, g, 2, 3)
+        l5 = linear_combination([g_feyn, g, g1, g2], [2, 5, 3, 9])
+        l6 = multi_product(g_feyn, g1, 2, 3)
+        l7 = multi_product(g_feyn, g, 2, 3)
+        l8 = multi_product([g_feyn, g, g1, g2], [2, 5, 3, 9])
+        r7 = multi_product(g, g, 2, 3)
+        r8 = multi_product([g, g, g1, g2], [2, 5, 3, 9])
+    catch
+        conversion_successful = false
+    end
+    @test conversion_successful
+    Graphs.optimize!([l1, l2, l3, l4, l5, l6, l7, r7, l8, r8])  # cache unique leaves
+
+    @test isequiv(l1, g + g1, :id)
+    @test isequiv(l2, g - g1, :id)
+    @test isequiv(l3, 2 * g + 3 * g1, :id)
+    @test isequiv(l4, linear_combination([g], [5]), :id)
+    @test isequiv(l5, linear_combination([g, g1, g2], [7, 3, 9]), :id)
+    @test isequiv(l6, multi_product(g, g1, 2, 3), :id)
+
+    # TODO: Refine multiple Prod -> Power conversion
+    @test_broken isequiv(l7, r7, :id)
+    @test_broken isequiv(l8, r8, :id)
+
+    # FeynmanGraph multiplication is undefined
+    err1 = AssertionError()
+    err2 = AssertionError()
+    try
+        g * g_feyn
+    catch err1
+    end
+    try
+        g_feyn * g
+    catch err2
+    end
+    @test err1 isa ErrorException
+    @test err2 isa ErrorException
+    @test err1.msg == "Multiplication of Feynman graphs is not well defined!"
+    @test err2.msg == "Multiplication of Feynman graphs is not well defined!"
+end
+
 @testset verbose = true "Evaluation" begin
     using FeynmanDiagram.ComputationalGraphs:
         eval!