From f74b48b8909a6c3ec7e96151eeef2f1dc195576b Mon Sep 17 00:00:00 2001
From: Marek Kaluba <kalmar@amu.edu.pl>
Date: Fri, 28 May 2021 14:20:17 +0200
Subject: [PATCH] separate SAut(F_n) from AutomorphismGroups

---
 src/Groups.jl                                 |  5 ++-
 src/{ => groups}/gersten_relations.jl         |  0
 src/groups/sautFn.jl                          | 34 +++++++++++++++++++
 .../transvections.jl}                         |  3 --
 src/new_autgroups.jl                          | 30 +---------------
 src/new_types.jl                              |  5 +++
 6 files changed, 42 insertions(+), 35 deletions(-)
 rename src/{ => groups}/gersten_relations.jl (100%)
 create mode 100644 src/groups/sautFn.jl
 rename src/{new_transvections.jl => groups/transvections.jl} (96%)

diff --git a/src/Groups.jl b/src/Groups.jl
index d2d477e..596e127 100644
--- a/src/Groups.jl
+++ b/src/Groups.jl
@@ -28,11 +28,10 @@ import OrderedCollections: OrderedSet
 include("new_types.jl")
 include("new_hashing.jl")
 include("normalform.jl")
-
-include("new_transvections.jl")
-include("gersten_relations.jl")
 include("new_autgroups.jl")
 
+include("groups/sautFn.jl")
+
 end # module New
 
 ###############################################################################
diff --git a/src/gersten_relations.jl b/src/groups/gersten_relations.jl
similarity index 100%
rename from src/gersten_relations.jl
rename to src/groups/gersten_relations.jl
diff --git a/src/groups/sautFn.jl b/src/groups/sautFn.jl
new file mode 100644
index 0000000..17ba331
--- /dev/null
+++ b/src/groups/sautFn.jl
@@ -0,0 +1,34 @@
+include("transvections.jl")
+include("gersten_relations.jl")
+
+function SpecialAutomorphismGroup(F::FreeGroup; ordering = KnuthBendix.LenLex, kwargs...)
+
+    n = length(KnuthBendix.alphabet(F)) ÷ 2
+    A, rels = gersten_relations(n, commutative = false)
+    S = KnuthBendix.letters(A)[1:2(n^2-n)]
+
+    rws = KnuthBendix.RewritingSystem(rels, ordering(A))
+    KnuthBendix.knuthbendix!(rws; kwargs...)
+    return AutomorphismGroup(F, S, rws, ntuple(i -> gens(F, i), n))
+end
+
+KnuthBendix.alphabet(G::AutomorphismGroup{<:FreeGroup}) = alphabet(rewriting(G))
+
+function relations(G::AutomorphismGroup{<:FreeGroup})
+    n = length(KnuthBendix.alphabet(object(G))) ÷ 2
+    return last(gersten_relations(n, commutative = false))
+end
+
+evaluate(f::FPGroupElement{<:AutomorphismGroup{<:FreeGroup}}) = evaluate!(domain(f), f)
+
+function evaluate!(
+    t::NTuple{N,T},
+    f::FPGroupElement{<:AutomorphismGroup{<:FreeGroup}},
+    tmp = one(first(t)),
+) where {T<:FPGroupElement,N}
+    A = alphabet(f)
+    for idx in word(f)
+        t = @inbounds evaluate!(t, A[idx], alphabet(object(parent(f))), tmp)::NTuple{N,T}
+    end
+    return t
+end
diff --git a/src/new_transvections.jl b/src/groups/transvections.jl
similarity index 96%
rename from src/new_transvections.jl
rename to src/groups/transvections.jl
index d8c8819..06a3737 100644
--- a/src/new_transvections.jl
+++ b/src/groups/transvections.jl
@@ -1,6 +1,3 @@
-abstract type GSymbol end
-Base.literal_pow(::typeof(^), t::GSymbol, ::Val{-1}) = inv(t)
-
 struct Transvection <: GSymbol
     id::Symbol
     ij::UInt8
diff --git a/src/new_autgroups.jl b/src/new_autgroups.jl
index d14e539..4122e58 100644
--- a/src/new_autgroups.jl
+++ b/src/new_autgroups.jl
@@ -12,26 +12,8 @@ struct AutomorphismGroup{G<:Group,T,R,S} <: AbstractFPGroup
 end
 
 object(G::AutomorphismGroup) = G.group
-
-function SpecialAutomorphismGroup(F::FreeGroup; ordering = KnuthBendix.LenLex, kwargs...)
-
-    n = length(KnuthBendix.alphabet(F)) ÷ 2
-    A, rels = gersten_relations(n, commutative = false)
-    S = KnuthBendix.letters(A)[1:2(n^2-n)]
-
-    rws = KnuthBendix.RewritingSystem(rels, ordering(A))
-    KnuthBendix.knuthbendix!(rws; kwargs...)
-    return AutomorphismGroup(F, S, rws, ntuple(i -> gens(F, i), n))
-end
-
-KnuthBendix.alphabet(G::AutomorphismGroup{<:FreeGroup}) = alphabet(rewriting(G))
 rewriting(G::AutomorphismGroup) = G.rws
 
-function relations(G::AutomorphismGroup)
-    n = length(KnuthBendix.alphabet(object(G))) ÷ 2
-    return last(gersten_relations(n, commutative = false))
-end
-
 function equality_data(f::FPGroupElement{<:AutomorphismGroup})
     imf = evaluate(f)
     # return normalform!.(imf)
@@ -107,16 +89,6 @@ Base.show(io::IO, A::AutomorphismGroup) = print(io, "automorphism group of ", ob
 domain(f::FPGroupElement{<:AutomorphismGroup}) = deepcopy(parent(f).domain)
 # tuple(gens(object(parent(f)))...)
 
-evaluate(f::FPGroupElement{<:AutomorphismGroup{<:FreeGroup}}) = evaluate!(domain(f), f)
+evaluate(f::FPGroupElement{<:AutomorphismGroup}) = throw("you need to implement `evaluate(::typeof(f))`")
 
-function evaluate!(
-    t::NTuple{N,T},
-    f::FPGroupElement{<:AutomorphismGroup{<:FreeGroup}},
-    tmp = one(first(t)),
-) where {T<:FPGroupElement,N}
-    A = alphabet(f)
-    for idx in word(f)
-        t = @inbounds evaluate!(t, A[idx], alphabet(object(parent(f))), tmp)::NTuple{N,T}
-    end
-    return t
 end
diff --git a/src/new_types.jl b/src/new_types.jl
index aff0f87..ca34915 100644
--- a/src/new_types.jl
+++ b/src/new_types.jl
@@ -197,3 +197,8 @@ function Base.show(io::IO, G::FPGroup)
     join(io, relations(G), ", ")
     print(io, "⟩")
 end
+
+## GSymbol aka letter of alphabet
+
+abstract type GSymbol end
+Base.literal_pow(::typeof(^), t::GSymbol, ::Val{-1}) = inv(t)