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    • CommentRowNumber1.
    • CommentAuthorelif
    • CommentTimeJun 27th 2014
    If there exists a crossed square (L,M,N,P), is there any isomorphism which satisfy (L⋊M)⋊(N⋊P)≅(L⋊N)⋊(M⋊P).
    • CommentRowNumber2.
    • CommentAuthorTim_Porter
    • CommentTimeJun 28th 2014

    Yes. This is to be found, I think, in one of Loday’s papers and possible in the paper by Ellis and Steiner. It is not that hard to define. It uses the h-function. In particular you can try it first for an inclusion crossed square coming from a group and two normal subgroups.

    • CommentRowNumber3.
    • CommentAuthorelif
    • CommentTimeNov 26th 2014
    how can I construct the actor object of crossed square? What kind of thigs will be changed as difference from crossed module or precrossed module?
    • CommentRowNumber4.
    • CommentAuthorTim_Porter
    • CommentTimeNov 27th 2014

    I presume you have looked at Norrie’s paper. Are you wanting a 2-actor for a crossed square or the construction of the actor part of the usual actor crossed square? It is not clear from your wording. You could look at Chris Wensley’s paper and preprints for more on actors from various viewpoints.

    • CommentRowNumber5.
    • CommentAuthorelif
    • CommentTimeNov 28th 2014
    I want to construct of 2-actor for a crossed square as an analogous of J.M Casas et al. (Actor of precrossed module). Which paper of Wensley's did you advice me? Thank you...
    • CommentRowNumber6.
    • CommentAuthorTim_Porter
    • CommentTimeNov 28th 2014
    • (edited Nov 28th 2014)

    You could try CHris Wensley’s article : Automorphisms and homotopies of groupoids and crossed modules (with Murat Alp,), Applied Categorical Structures: “http://dx.doi.org/10.1007/s10485-008-9183-y

    It is not clear to me how to construct a 2-actor for a crossed square. Have you tried to construct such a gadget for a 2-crossed module?

    • CommentRowNumber7.
    • CommentAuthorelif
    • CommentTimeNov 29th 2014
    Not yet. But I will try to construct it very soon. Thaks for your comments...