Rotation numbers have played a central role in the study of (unforced) monotone circle maps. In such a case it is possible to obtain a priori bounds of the form »¡ 1=n μ ...1=n†...yn ¡ y0† μ »‡ 1=n, where ...1=n†...yn ¡ y0† is an estimate of the rotation number obtained from an orbit of length n with initial condition y0, and » is the true rotation number. This allows rotation numbers to be com...

Let E(·) : R → B(X) be the spectral decomposition of a trigonometrically well-bounded operator U acting on the arbitrary Banach space X, and suppose that the bounded function φ : T → C has the property that for each z ∈ T, the spectral integral R [0,2π] φ(e)dEz(t) exists, where Ez(·) denotes the spectral decomposition of the (necessarily) trigonometrically well-bounded operator (zU). We show th...

We give an equivalent condition for the existence of a semi-conjugacy to an irrational rotation for conservative homeomorphisms of the two-torus. This leads to an analogue of Poincaré's classification of circle homeomorphisms for conservative toral homeomor-phisms with unique rotation vector and a certain bounded mean motion property. For minimal toral homeomorphisms, the result extends to arbi...

We give an equivalent characterisation of the semi-conjugacy class of an irrational rotation within the space of conservative homeomorphisms of the two-torus. This leads to an analogue of Poincaré’s classification of circle homeomorphisms for conservative toral homeomorphisms with unique rotation vector and a certain bounded mean motion property. For minimal toral homeomorphisms, the result ext...

We prove an analogue of Poincaré’s classification of circle homeomorphisms for conservative homeomorphisms of the two-torus with unique rotation vector and a certain bounded mean motion property. In particular, this provides an equivalent characterisation of the semi-conjugacy class of an irrational rotation within the space of conservative toral homeomorphisms. For minimal toral homeomorphisms...

An n-Venn diagram is a Venn diagram on n sets, which is defined to be a collection of n simple closed curves (Jordan curves) C1, C2, ..., Cn in the plane such that any two intersect in finitely many points and each of the 2n sets of the form Ë Cie is nonempty and connected, where ei is one of "interior" or "exterior". Thus the Venn regions are all bounded except for the region exterior to all c...