Abstract
We determine the structure of semigroups that satisfy xyzw∈{xy,xw,zy,zw}. These semigroups are precisely those whose power semigroup is a generalised inflation of a band. The structure of generalised inflations of the following types of semigroups is determined: the direct product of a group and a band, a completely simple semigroup and a free semigroup F(X) on a set X. In the latter case the semigroup must be an inflation of F(X). We also prove that in any semigroup that equals its square, the power semigroup is a generalised inflation of a band if and only if it is an inflation of a band.
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Communicated by Thomas E. Hall.
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Monzo, R.A.R. Further results in the theory of generalised inflations of semigroups. Semigroup Forum 76, 540–560 (2008). https://doi.org/10.1007/s00233-008-9055-7
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DOI: https://doi.org/10.1007/s00233-008-9055-7