Group closures of partial transformationsSpringer Science and Business Media LLC - Tập 65 - Trang 301-313 - 2001
Inessa Levi, Japheth Wood
Let \(X\) be an infinite set, \(f\) a partial one-to-one transformation of \(X\), and \(H\) a normal subgroup of G
X
, the group of all permutations of \(X\). We investigate when \(H\) is equal to \(G_{}\). That is, we are interested when \(H\) is the full group of normalizers of the semigroup of transformations on \(X\) generated by conjugates of \(f\) by e...... hiện toàn bộ
On exposed semigroup homomophinsSpringer Science and Business Media LLC - Tập 13 - Trang 189-204 - 1976
Benno Fuchssteiner
In the main theorem of this paper the existence of weakly exposed semigroup homomorphisms is proved. This theorem is effectively equivalent to the axiom of choice and generalizes some well known theorems of functional analysis like the Hahn-Banach theorem, the Krein-Milman theorem, Bauer's minimum principle and a result of T. Husain and I. Tweddle.