We construct a modification of Churchill and Trotter’s trifree objects in e-varieties of locally E-solid
semigroups, which have the property, for e-varieties of locally inverse semigroups and for e-varieties of Esolid
semigroups, of being isomorphic to the bifree objects.
Hall, T.E., Yeh, Y.T. (2001), Trifee objects in e-varieties of locally e-solid semigroups, Research Letters in the Information and Mathematical Sciences, 2, 89-92