Group actions on topological graphs

On the topological centers of module actions

In this paper, we  study the Arens regularity properties of module actions. We investigate some properties of topological centers of module actions ${Z}^ell_{B^{**}}(A^{**})$ and  ${Z}^ell_{A^{**}}(B^{**})$ with some conclusions in group algebras.

Maximal harmonic group actions on finite graphs

This paper studies groups of maximal size acting harmonically on a finite graph. Our main result states that these maximal graph groups are exactly the finite quotients of the modular group Γ = 〈 x, y | x = y = 1 〉 of size at least 6. This characterization may be viewed as a discrete analogue of the description of Hurwitz groups as finite quotients of the (2, 3, 7)-triangle group in the context...

ON TOPOLOGICAL ENTROPY OF GROUP ACTIONS ON Sl

In this paper, we show that a surface group action on Sl with a non-zero Euler number has a positive topological entropy. We also show that if a surface group action on Sl has a Euler number which attains the maximal absolute value in the inequality of Milnor-Wood, then the topological entropy of the action equals the exponential growth rate of the group.

Topological Obstructions to Certain Lie Group Actions on Manifolds

Given a smooth closed S1-manifold M , this article studies the extent to which certain numbers of the form (f∗ (x) · P · C) [M ] are determined by the fixed-point set MS 1 , where f : M → K (π1 (M) , 1) classifies the universal cover of M , x ∈ H∗ (π1 (M) ;Q), P is a polynomial in the Pontrjagin classes of M , and C is in the subalgebra of H∗ (M ;Q) generated by H2 (M ;Q). When MS 1 = ∅, variou...

Topological Centers of Certain Banach Module Actions