Merge pull request #29 from kalmarek/fix/#28_normalform_hashing

Fix for #28: normalform & hashing

Project.toml

@@ -1,7 +1,7 @@
 name = "Groups"
 uuid = "5d8bd718-bd84-11e8-3b40-ad14f4a32557"
 authors = ["Marek Kaluba <kalmar@amu.edu.pl>"]
-version = "0.7.6"
+version = "0.7.7"
 
 [deps]
 GroupsCore = "d5909c97-4eac-4ecc-a3dc-fdd0858a4120"

src/aut_groups/transvections.jl

@@ -14,12 +14,7 @@ end
 λ(i, j) = Transvection(:λ, i, j)
 
 function Base.show(io::IO, t::Transvection)
-    id = if t.id === :ϱ
-        'ϱ'
-    else # if t.id === :λ
-        'λ'
-    end
-    print(io, id, subscriptify(t.i), '.', subscriptify(t.j))
+    print(io, t.id, subscriptify(t.i), '.', subscriptify(t.j))
     return t.inv && print(io, "^-1")
 end
 

src/hashing.jl

@@ -37,6 +37,7 @@ function _update_savedhash!(g::AbstractFPGroupElement, data)
 end
 
 function Base.hash(g::AbstractFPGroupElement, h::UInt)
+    g = normalform!(g)
     _isvalidhash(g) || _update_savedhash!(g, equality_data(g))
     return hash(g.savedhash >> count_ones(__BITFLAGS_MASK), h)
 end

src/matrix_groups/eltary_symplectic.jl

@@ -23,7 +23,7 @@ end
 
 function Base.show(io::IO, s::ElementarySymplectic)
     i, j = Groups.subscriptify(s.i), Groups.subscriptify(s.j)
-    print(io, s.symbol, i, j)
+    print(io, s.symbol, i, '.', j)
     return !isone(s.val) && print(io, "^$(s.val)")
 end
 

src/types.jl

@@ -88,6 +88,9 @@ end
 
 abstract type AbstractFPGroupElement{Gr} <: GroupElement end
 
+Base.copy(g::AbstractFPGroupElement) = one(g) * g
+word(f::AbstractFPGroupElement) = f.word
+
 mutable struct FPGroupElement{Gr<:AbstractFPGroup,W<:AbstractWord} <:
                AbstractFPGroupElement{Gr}
     word::W
@@ -111,7 +114,9 @@ function Base.show(io::IO, ::Type{<:FPGroupElement{Gr}}) where {Gr}
     return print(io, FPGroupElement, "{$Gr, …}")
 end
 
-word(f::AbstractFPGroupElement) = f.word
+function Base.copy(f::FPGroupElement)
+    return FPGroupElement(copy(word(f)), parent(f), f.savedhash)
+end
 
 #convenience
 KnuthBendix.alphabet(g::AbstractFPGroupElement) = alphabet(parent(g))
@@ -134,7 +139,13 @@ function Base.:(==)(g::AbstractFPGroupElement, h::AbstractFPGroupElement)
 end
 
 function Base.deepcopy_internal(g::FPGroupElement, stackdict::IdDict)
-    return FPGroupElement(copy(word(g)), parent(g), g.savedhash)
+    haskey(stackdict, objectid(g)) && return stackdict[objectid(g)]
+    cw = if haskey(stackdict, objectid(word(g)))
+        stackdict[objectid(word(g))]
+    else
+        copy(word(g))
+    end
+    return FPGroupElement(cw, parent(g), g.savedhash)
 end
 
 function Base.inv(g::GEl) where {GEl<:AbstractFPGroupElement}

src/wl_ball.jl

@@ -26,8 +26,7 @@ function wlmetric_ball(
                 new = collect(
                     op(o, s) for o in @view(ball[sizes[end-1]:end]) for s in S
                 )
-                append!(ball, new)
-                unique!(ball)
+                ball = union!(ball, new)
                 push!(sizes, length(ball))
             end
         end

test/fp_groups.jl

@@ -14,7 +14,8 @@
     G = FPGroup(F, [a * b => b * a, a * c => c * a, b * c => c * b])
 
     @test G isa FPGroup
-    @test sprint(show, G) == "⟨ a  b  c | \n\t  a*b => b*a  a*c => c*a  b*c => c*b ⟩"
+    @test sprint(show, G) ==
+          "⟨ a  b  c | \n\t  a*b => b*a  a*c => c*a  b*c => c*b ⟩"
     @test rand(G) isa FPGroupElement
 
     f = a * c * b
@@ -40,7 +41,7 @@
     end
 
     # quotient of G
-    H = FPGroup(G, [aG^2 => cG, bG * cG => aG], max_rules=200)
+    H = FPGroup(G, [aG^2 => cG, bG * cG => aG]; max_rules = 200)
 
     h = H(word(g))
 
@@ -48,15 +49,21 @@
     @test_throws AssertionError h == g
     @test_throws MethodError h * g
 
-    H′ = FPGroup(G, [aG^2 => cG, bG * cG => aG], max_rules=200)
+    H′ = FPGroup(G, [aG^2 => cG, bG * cG => aG]; max_rules = 200)
     @test_throws AssertionError one(H) == one(H′)
 
     Groups.normalform!(h)
     @test h == H([5])
 
-    @test_logs (:warn, "using generic isfiniteorder(::AbstractFPGroupElement): the returned `false` might be wrong") isfiniteorder(h)
+    @test_logs (
+        :warn,
+        "using generic isfiniteorder(::AbstractFPGroupElement): the returned `false` might be wrong",
+    ) isfiniteorder(h)
 
-    @test_logs (:warn, "using generic isfinite(::AbstractFPGroup): the returned `false` might be wrong") isfinite(H)
+    @test_logs (
+        :warn,
+        "using generic isfinite(::AbstractFPGroup): the returned `false` might be wrong",
+    ) isfinite(H)
 
     Logging.with_logger(Logging.NullLogger()) do
         @testset "GroupsCore conformance: H" begin
@@ -64,4 +71,24 @@
             test_GroupElement_interface(rand(H, 2)...)
         end
     end
+
+    @testset "hash/normalform #28" begin
+        function cyclic_group(n::Integer)
+            A = Alphabet([:a, :A], [2, 1])
+            F = FreeGroup(A)
+            a, = Groups.gens(F)
+            e = one(F)
+            Cₙ = FPGroup(F, [a^n => e])
+
+            return Cₙ
+        end
+
+        n = 15
+        G = cyclic_group(n)
+        ball, sizes = Groups.wlmetric_ball(gens(G); radius = n)
+        @test first(sizes) == 2
+        @test last(sizes) == n
+
+        @test Set(ball) == Set([first(gens(G))^i for i in 0:n-1])
+    end
 end