isrimhook is incorrect?

[kalmarek]

While working on my own code for YoungDiagrams I encountered this:

λ = [5,3,2,2,1]
μ = [2,2,1]

m, n = length(λ), length(μ)
l = maximum(λ)
youngdiagram=zeros(Int, m, l)
for i=1:n
    youngdiagram[i, μ[i]+1:λ[i]]=1
end
for i=n+1:m
    youngdiagram[i, 1:λ[i]]=1
end
youngdiagram

produces

5×5 Array{Int64,2}:
 0  0  1  1  1
 0  0  1  0  0
 0  1  0  0  0
 1  1  0  0  0
 1  0  0  0  0

which is clearly not a rimhook (it's disconnected). however Combinatorics.isrimhook((λ, μ)) returns true.

Am I missing something obvious?

[mschauer]

Looks like it checks for "having a neighbour" https://github.com/JuliaMath/Combinatorics.jl/blob/master/src/youngdiagrams.jl#L78 instead of connectedness, as in you example every cell has a neighbour but the diagram is not connected.

[kalmarek]

https://github.com/Nemocas/AbstractAlgebra.jl/blob/b0bcc77ba64d97cd8a3c2e57b1bfe7cad20db5c0/src/generic/YoungTabs.jl#L860

[kalmarek]

what license do you need to just copy my code?

[mschauer]

Can you check if there is something in https://github.com/JuliaMath/Combinatorics.jl/blob/master/src/youngdiagrams.jl which is not covered by your code? If would almost propose to remove it here and refer to https://github.com/Nemocas/AbstractAlgebra.jl for the functionality.

[mschauer]

Otherwise if you wrote the code in question, than you allow the use of the code under MIT for this package by saying so.

[kalmarek]

You can use the code in YoungDiags under MIT license;

Looking very briefly, all of that is covered in AbstractAlgebra.jl