26 lines
864 B
Julia
26 lines
864 B
Julia
include("transvections.jl")
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include("gersten_relations.jl")
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function SpecialAutomorphismGroup(F::FreeGroup; ordering = KnuthBendix.LenLex, kwargs...)
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n = length(alphabet(F)) ÷ 2
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A, rels = gersten_relations(n, commutative=false)
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S = [A[i] for i in 1:2:length(A)]
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maxrules = 1000*n
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rws = KnuthBendix.RewritingSystem(rels, ordering(A))
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Logging.with_logger(Logging.NullLogger()) do
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# the rws is not confluent, let's suppress warning about it
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KnuthBendix.knuthbendix!(rws; maxrules=maxrules, kwargs...)
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end
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return AutomorphismGroup(F, S, rws, ntuple(i -> gens(F, i), n))
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end
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KnuthBendix.alphabet(G::AutomorphismGroup{<:FreeGroup}) = alphabet(rewriting(G))
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function relations(G::AutomorphismGroup{<:FreeGroup})
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n = length(alphabet(object(G))) ÷ 2
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return last(gersten_relations(n, commutative = false))
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end
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