Semigroup Forum (2018) 96:603–607
Erratum to: Algebras of Ehresmann semigroups
Received: 4 May 2017 / Accepted: 30 July 2017 / Published online: 21 August 2017
© Springer Science+Business Media, LLC 2017
Erratum to: Semigroup Forum
Shoufeng Wang discovered an error in the main theorem of the author’s Semigroup
Forum article ‘Algebras of Ehresmann semigroups and categories’. Wang observed
that the function we suggest as an isomorphism is not a homomorphism unless the
semigroup being discussed is left restriction. In order to ﬁx our mistake, we will add
this assumption. Note that our revised result is still a generalization of earlier work of
Guo and Chen, the author, and Steinberg.
1 A correction to the main theorem of 
Shoufeng Wang  has observed that the proof of [3, Theorem 3.4] does not hold
without the additional assumption that the semigroup is left restriction. This Erratum
shows how this assumption yields a valid result, and examines the consequences.
Theorem 1.5, which is the revision of [3, Theorem 3.4], nevertheless generalizes [5,
Theorem 4.2], [2, Theorem 4.2] and [4, Proposition 3.2].
We assume the reader is familiar with  and in particular with the deﬁnition of an
E-Ehresmann semigroup; for undeﬁned terms, the reader should consult .
Communicated by Victoria Gould.
The online version of the original article can be found under doi:10.1007/s00233-016-9838-1.
Department of Mathematics, Bar Ilan University, 52900 Ramat Gan, Israel