Countably determined ends and graphs

نویسندگان

چکیده

The directions of an infinite graph G are a tangle-like description its ends: they choice functions that choose component G−X for all finite vertex sets X⊆V(G) in compatible manner. Although every direction is induced by ray, there exist graphs not uniquely determined any countable subset their choices. We characterise these and countably counterparts terms star-like substructures or rays the graph. Curiously, whose but which cannot be distinguished at once many structurally can choices, we this Our characterisations phrased normal trees tree-decompositions. four (sub)structural imply combinatorial classes defined first second axiom countability applied to end spaces: two spaces countable, respectively, complements classes.

برای دانلود رایگان متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Weakly Countably Determined Spaces of High Complexity

We prove that there exist weakly countably determined spaces of complexity higher than coanalytic. On the other hand, we also show that coanalytic sets can be characterized by the existence of a cofinal adequate family of closed sets. Therefore the Banach spaces constructed by means of these families have at most coanalytic complexity.

متن کامل

Borel and countably determined reducibility in nonstandard domain

We consider, in a nonstandard domain, reducibility of equivalence relations in terms of the Borel reducibility ≤B and the countably determined (CD, for brevity) reducibility ≤CD. This reveals phenomena partially analogous to those discovered in modern “standard” descriptive set theory. The ≤CD-structure of CD sets (partially) and the ≤B-structure of Borel sets (completely) in N is described. We...

متن کامل

Some Ramsey-type theorems for countably determined sets

Let X be an infinite internal set in an ω1-saturated nonstandard universe. Then for any coloring of [X]k, such that the equivalence E of having the same color is countably determined and there is no infinite internal subset of [X]k with all its elements of different colors (i.e., E is condensating on X), there exists an infinite internal set Z ⊆ X such that all the sets in [Z]k have the same co...

متن کامل

ON NEW CLASSES OF MULTICONE GRAPHS DETERMINED BY THEIR SPECTRUMS

A multicone graph is defined to be join of a clique and a regular graph. A graph $ G $ is cospectral with graph $ H $ if their adjacency matrices have the same eigenvalues. A graph $ G $ is said to be determined by its spectrum or DS for short, if for any graph $ H $ with $ Spec(G)=Spec(H)$, we conclude that $ G $ is isomorphic to $ H $. In this paper, we present new classes of multicone graphs...

متن کامل

Introduction to Ends of Graphs

We give an elementary introduction to the theory of ends of locally finite graphs for students and mathematicians from other fields. The focus is on basic topological properties of the end space. We will also discuss Cayley graphs and some connections between ends and group actions on graphs.

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

ژورنال

عنوان ژورنال: Journal of Combinatorial Theory, Series B

سال: 2022

ISSN: ['0095-8956', '1096-0902']

DOI: https://doi.org/10.1016/j.jctb.2022.04.002