kalmar/Groups.jl
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findnext and findfirst for GWords

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kalmar 2017-01-25 11:30:46 +01:00
parent c7e3c0b403
commit b0b129fd8b
1 changed files with 23 additions and 0 deletions
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src/Groups.jl
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@ -176,6 +176,29 @@ end
is_subsymbol(s::GSymbol, t::GSymbol) =
s.gen == t.gen && (0 ≤ s.pow ≤ t.pow || 0 ≥ s.pow ≥ t.pow)
function Base.findnext(W::GWord, Z::GWord, i::Integer)
n = length(Z.symbols)
@assert n > 1
for (idx,a) in enumerate(W.symbols[i:end])
if idx + n - 1 > length(W.symbols)
break
end
first = is_subsymbol(Z.symbols[1],a)
if first
middle = W.symbols[i+idx:i-1+idx+n-2] == Z.symbols[2:end-1]
last = is_subsymbol(Z.symbols[end], W.symbols[i-1+idx+n-1])
if middle && last
return i-1 + idx
end
end
end
return 0
end
Base.findfirst(W::GWord, Z::GWord) = findnext(W, Z, 1)
include("free_groups.jl")
include("automorphism_groups.jl")